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coarsest of grass, to which no living animal would On the 4th of August last, I received by post from care to give a passing glance. All the strata are cut | Mr. W. R. Jeffrey, of Ashford, Kent, a small batch of through ; when sinking a pit the rubbish is sent | seven of these eggs which had been laid on glass away. When the pit gets under way, falls of shale some time on the morning of the end. The batch are almost of daily occurrence, and the greater part had a somewhat greasy whitish appearance, and on of this shale has to be brought away, which soon closer inspection the eggs were seen to be arranged makes the heaps grow larger. The geologist will in an oval or ring of six surrounding a central one, perhaps find in no part of the world so rich in fossil but all overlapping, in such a manner that the central
egg was overlain by three at one end of the oval, and overlay the three at the other end; whilst of the former three the middle (or remotest) egg overlapped the other two, and of the latter three the middle (or nearest) egg was overlapped by them. The lateral pair of the first three also overlapped the lateral pair of the second three, but the eggs of each pair did not touch each other. In this arrangement there was one egg (only) at the nearest extremity of the long
axis of the group, which lay directly on the glass Fig. 29. - Anthracosia ovata, a common fossil in coal shales. without overlying a part of any other; and one
(only) at the other extremity of the axis, which, remains, as those refuse shale heaps, met with at our overlying two others in part, was itself not overlapped colliery places. If he were to split some of the shale by any other. The conclusion appears inevitable open, he might find abundance of fossil mussels, such that these eggs were respectively the first and last as Anthracosia, as well as of fossil ferns and other laid in the group: otherwise a later egg must have plant remains, and thus discover that even in our been partially inserted beneath one already deposited district there is plenty of interest, although it is only on the glass—a supposition which the character of a Pit one!
the eggs themselves would appear to negative JOHN SIM.
decidedly. I found it convenient, taking the longer Northumberland.
axis of the group as a meridian running north and south, and designating the central egg as “C” to
distinguish the others by the points of the compass, ON THE EMBRYOLOGY OF BOTYS as N., S., N.W., &c., and regarding the group always HYALINALIS
from the free side. The moth, then, in depositing her
eggs, must have proceeded along the glass in a general ' By DR. J. A. OSBORNE.
direction from south to north ; and the eggs must have ; HILST according the first place in embryo. been laid in the following order :-S., S.W. and S.E.,
logical research to the method of investiga C., N.W., and N.E., N. The order of precedence in tion by means of sections, Dr. August Weismann, the lateral pairs is not determinable from these premises. in his latest work (“ Beitr. z. Kenntniss d. .ersten Subsequently Mr. Jeffrey sent me the shells of another Entwickelungsvorgänge im Insektenei,” Bonn, 1882), group of nine of these eggs, laid at the same time, is yet of opinion that the older method, by “contin which give some further insight into the method of uous observation of the living and developing egg,” oviposition. In this group, which has a transversely has of late years been much underrated. “There elongated rhomboidal form, the extreme lateral eggs, are,” he says (loc. cit. p. 2), “certainly phenomena E. and W., which were absent in the first, are present. of development, where the method by section fails us | Here it is plain that the eggs were laid in rows of altogether, and of whose course, nay, very existence, three each, forming an acute angle with the meridian, only direct observation gives us any intelligence.” and each row beginning a step further east or west and Perhaps there are few eggs of insects which, owing to further north than the row before it. The order must their extreme flatness and transparency, are better (most likely) have been S., S.W., W.; S.E., C., N. W. ; suited for direct observation during development than E., N.E., N. ; or else, S., S.E., E. ; S.W., C., N.E. ; those of Botys hyalinalis. They are small oval discs W., N.W., N. I enclose diagrams (Figs. 30 and 31), of about 2-3'-2.5 mm. in length by 2 mm. or rather the better to illustrate my meaning, but if it should more in breadth, not thicker in proportion than the be inconvenient to engrave these, the grouping may body of a sole or plaice is to its diameter, and thin be very well imitated with the requisite number of ning off in like manner to a sharp edge at the pence or half-pence, taking the vertical line of the circumference. The shell is transparent as glass, and figure on the coin to represent the long axis of the the view but little impeded by the somewhat coarse egg. In all cases the long axis of the egg-oval lay reticulations of the chorion in irregularly polygonal north and south, i.e. parallel with the meridian of the fields with linear borders and uneven areas.
group ; and, as subsequent observation showed, in
all cases the head of the embryo lay south. The | lower pole, we arrive at the conclusion (somewhat question now arises : does the south end of the egg important, inasmuch as it is at variance with the correspond with its lower pole or first laid end? | statement of Leuckart that “the upper pole in all This question must be answered affirmatively, unless cases contains the head end of the embryo.”-See we are prepared to admit either, on the one hand Entom. Month. Mag. vol. xx. p. 146), that in these that the eggs in Jaying could have been partly slid eggs the head of the embryo normally occupies the under ones already laid, which their thinness and lower pole of the egg. The physiological reason is delicacy and their firm adhesion to the glass and to obvious. In those cases where (as in Pieris brassicæ) the one another seems to render impossible ; or, on the egg is attached by its lower pole to the food-plant, other hand, that the ovipositor of the moth, whilst the escaping larva, if its head occupied that end,
depositing the egg is bent in under her venter so as to extrude the egg with its lower pole to the front Such an inversion of the normal orientation does take place in the case of the sawfly (Zaræa fasciata), and probably also, more or less, in the case of other insects laying their eggs in mines or in the ground, or in other situations where a long ovipositor is required, but I am ignorant that there are any grounds for such an assumption in the case of Botys. Taking it for granted then that the south end of the egg is its
would not only have to eat its way out of the shell, but also through the substance to which the egg was attached ; while in the case of Botys if the head of the larva occupied the upper pole, it would, after eating its way through its own shell, come in contact with the egg above it with disadvantage to itself and probable destruction to its neighbour.
When I received the eggs on the 4th of August, they were already in the third day of incubation, and presented the following appearances. The yolkgranules were aggregated in spherular masses, which another. The inner of these, continuous with the again were arranged in two groups : an annular embryo itself, and lying immediately over it, is the larger mass having a clear space outside between it amnion; the outer, continuous with the blastoderm and the shell, and a clear central area in which the surrounding the yolk, is the serous membrane. Two smaller mass lay in an irregularly curved spiral or sacs are thus formed, the one within the other, and crescentic form. For the sake of convenience, I shall between them lies the yolk. In the lepidopterous call these two masses of jopaque yolk the Annulus egg the yolk next finds its way into the space and the Spiral. The former was composed of yolk between the amnion and the serous membrane, flow. spherules (i.e. aggregated masses of yolk-granules), ing over the former, and depressing it and the arranged, somewhat loosely at first, but by degrees embryo beneath it till both are completely submerged more compactly, so as to flatten their sides and give in yolk and consequently hidden from view. But them a polygonal form, in a flat oval ring, having the owing to the extreme flatness of the Botys' eggs, little same contour as the egg itself, but gradually wider at or no yolk finds its way to the sides of the embryo, one end than the other, not unlike a horse-collar. but is constrained to lie in a ring around it, leaving The broader end was at first in all cases (except, the centre clear, except that part immediately perhaps, N.W.) towards the south end of the egg.* beneath the germinal stripe, which by the involution It maintained its shape with little change, except of the two extremities of the embryo becomes soon some diminution in width and increase in density, reduced to a narrow capitate peduncle, the “ umbilical all the time that the eggs were under observation, i.e. stalk,” &c. (Fig. 33). till the gth August, when they were unfortunately A glance at the diagrams (Figs. 30 and 31), will destroyed by an accident a day or two before show that the umbilicus did not lie unisormly in hatching would have taken place. The spiral, on one direction east or west. When it had its the contrary, was constantly undergoing change,
attachment to the annulus on the west, this meant and it soon became evident that its convex border that the venter of the embryo was facing east, and was the true seat of development. Regarded as a that (having its head south) it was lying on its right mass of unchanged yolk, it had, on the 5th August, side or with its right side next the glass : and vice somewhat the appearance of a double scroll (Fig. 32),
verså. This arrangement may be very well imitated something like the capital of an Ionic pillar, and with the half-pence by placing them upside-down, with a stalk between roughly corresponding to the and with the queen's head up to represent the embryo shaft of the pillar, or, at least, the upper end of it. on its right side, and the figure of Britannia up to The volutes of this scroll or double spiral were not represent it lying on its left side with the venter similar. One was sharp, dark and well defined ; looking west. The only thing to be noted in this the other vague and changing, and made up of looser connection (and the small number of the total granules of yolk. In all cases the sharper well | observations makes it the less reliable), is that in defined volute lay towards the north. The stalk or both* groups of eggs all the lateral eggs, i.e. those shaft between the volutes pointed in a general direc not situated on the central axis or meridian of the tion east or west, and after some hours became more group, had their umbilici directed towards the slender and formed an attachment with the annulus meridian, and their ventres consequently looking on the inside. At this time the scroll was not unlike outwards. To this statement there were two excepthe vertebrate embryo in an early stage with its tions in the group of nine ; viz. N. W., which did not umbilical stalk, and, as no doubt yolk granules passed develop at all, and N.E., which had its venter looking into the embryo by this channel, there may have inwards, but failed to hatch out. been something functional in the resemblance as There was a considerable difference in the rate of well.
development of the different eggs in the group of To explain this annular arrangement of the food seven. S.W. appeared to be the most advanced, yolk it is necessary to refer to the formation of the although latterly N.E. was not much if anything amnion. After the yolk has become surrounded by behind it. But N.W. was all along several hours the growth of cells called the blastoderm, and after
behind the others in its development. These might be the germinal stripe, or foundation of the embryo, arranged in the order of development thus :--S., S.E., has been differentiated along one side of this blasto N., C.; but with smaller differences between them. derm, a double fold of the latter grows up all round On the evening of the 6th August the umbilical stalk the circumference of the germinal stripe and finally and spiral had dwindled to a small dense inverted closes in over it, the edges of the fold fusing together cone with a rounded base and having its apex at the and the two layers (of blastoderm) of which it is annulus (v. Fig. 33). On its north side a sort of composed at the same time separating from one notch separated the sharp curved bird-like beak from
the rest of the stalk. The clear central area was * Under date August 7th, I have the following note. "In the three northern cggs it is the northern half which is widest now-in the three southern, the southern half, and more dis * In the group of nine eggs I deduce this from Mr. Jeffrey's tinctly so.".
observations communicated by letter.
therefore much increased in size, but not so limpidly | forwards in place of Lackwards as at first. The transparent as the (empty ?) space surrounding the middle of the bend of the abdomen (at the incurvature) annulus externally. Immediately within the annulus, was between the third and fourth abdominal segments; on the morning of the 7th, I observed the clear area at I P.M. the tail had come quite up with the foreall round to the peduncle or umbilicus on both sides, feet ; at 2.40 P.M. it reached fully up to the head and to have its outer edge crenated. In the more advanced fully filled the larger northern bay. At this time the eggs these crenations soon developed into a row of stump of the umbilicus on the one hand, now reduced (ventral) segments, twelve in number, marked off from to a mere conical point, and a similar projection from the rest of the central area by a curved concentric line. the opposite side of the annulus, where cloudlets of These segments had an optical area from four to six yolk-granules were passing in towards the neck times as large as the reticulations of the chorion (say region (see Fig. 34), indicated a division of the whole about to inch in diameter). Soon three of them, interior space into two unequal bays, of which the at the south extremity of the series, appeared larger smaller (southern) contained the head, and the other than the rest and furnished with processes sloping the rest of the body. The second abdominal segment northward ; whilst still further to the south, but less might be said to form the keystone of the arch where distinctly, two or three other segments could be made the abdomen was bent on itself, but the head, though out having also processes sloping in the opposite free in its bay, remained mostly in close contact direction. Into this space, corresponding to the
with the umbilical stalk. On the morning of the 9th region between the head and the body, faint cloudlets the tail reached quite to the level of the head and of yolk-granules appeared as it were passing in from beyond the eye-spots. The embryo lay in a loop the annulus towards the central area. Owing with the legs inside, a position which it had reached probably to the sloping in opposite directions of the by the growth and enlargement of the tail without any thoracic and cephalic processes, there was less pressure change of place in the head and anterior segments. here of the amnion against the serous membrane and I have dwelt at some length on this incurvature freer passage for the yolk. This appearance at this and growth of the tail by which the lepidopterous region was visible persistently, in all the eggs (Fig. 34). embryo attains the loop-form in the shell, because The thoracic processes or legs were about half the Kowalevski has stated (Mém. de l'Acad. Imp. des width of the segments from the posterior half of which Sciences de St. Pétersbourg, vii. série, tome xvi. they took their origin, but considerably longer, | No. 12, p. 56), that it does so by the whole embryo passing out of sight in the annulus (Fig. 34). About turning round in the shell after its tail. “Dem this time I noticed also other appearances as of Hinterende folgend, dreht sich der ganze Embryo so, curved concentric lines marking out a tube dass er jetzt der ihn noch bedeckenden serösen (mesenteron?) but which would require further Hülle den Rücken zuwendet, und die Extremitäten observation for their certain interpretation. Upon the erscheinen nach innen gerichtet.” Perhaps the same day (Aug. 7) in the afternoon, I noticed eye subject may be made clearer by a brief consideration spots (in all but N.W.) a group of about six arranged of the different kinds of motion which may be in a circular form (Fig. 35). There were now visible at observed in eggs. These may be classed under four least four cephalic segments, and it was at the base heads. ist. Movements due to gravitation. The of the third (reckoning from behind forwards) that ventral or developing side of the yolk in the egg of the group of eye-spots was situated. Later on I saw Gastrophysa raphani, e.g., turns always towards the a fifth larger terminal mass forming the extreme upper surface, though this change takes place so anterior extremity of the embryo. The thoracic legs slowly that it may occupy several days in compleappeared to be jointed. At 2.50 P.M. I noticed that tion. 2nd. Movements of growth ; strikingly illusthe twelfth (ninth abdominal) segment was somewhat trated in the egg of Calopteryx, in which the embryo longer than the others and projected inwards towards becomes inverted in the shell (v. Balfour, Comp. Emthe centre, beyond their level. At 6.55 P.M. this bryol. i. 334). 3rd. Embryonic movements; by which inward projection had disappeared, and a very im- limbs or parts show movements without any change portant change in the terminal segment had been of place in the whole ; and, lastly, larval movements; initiated. It had become ventrally incurved upon when the perfectly formed embryo changes its position itself (Fig. 36). This segment was elongated, and in the shell, or acts in any other way as if it were narrowed at the apex. It advanced steadily forwards independent of it. The loop form of the lepidopalong the ventral aspect of the embryo, followed by terous embryo, Kowalevski supposes to be due to the the others, and growing larger at the same time; but latter class of movements, whilst in reality it is only the head remained always in its original place. On a movement of growth. When, in its final stages, as the morning of the 8th the last three segments (10-12) stated by Kowalevski and as observed in these eggs were round the corner (Fig. 37); at 9.10 A.M. the tail by Mr. Jeffrey, the embryo of Botys devours the was in contact with the metathoracic legs; at 12.45 remainder of the yolk and cuts its way out of the P.M. it had gone beyond the two posterior pairs of shell, these actions may be fairly described as larval legs, which, with the forelegs, were now directed movements.
On the afternoon of the Ah August, I had a pretty | been fortunate enough, thanks to Mr. Jeffrey's clear view of the head inobscured by the annulus. kindness, to see, is not without some interest and The four processes were approximated like the importance from its bearing on two points: the fingers of the hand, wlilst the fifth or terminal lobe orientation of the embryo in the shell, and the lay away from theri like a thumb (Fig. 38). Pro- incurvature of the tail. If there were any certainty jecting into the bay between the thumb and the of obtaining similar eggs another season, I wond fingers, and crossing the latter obliquely, there was have reserved some of the other points for further faintly visible another process which I was unable to observation : as it is, I cannot refrain from mentioning follow further. On the other side of the umbilical the hypothesis that, as plants are bent to or from the stalk, now worn down to a conical stump, a dense light by a preponderance of growth on the opposite crescentic streak of yoke had been as it were detached side, so, here, the proximate cause of the ventral and carried away by the growth of the tail till it curvature of the tail end is the later, but then came to occupy the northern curve of the bay. quicker and predominant growth of the dorsal section This included yolk, according to Kowalevski, marks of the embryo. the extent of the mesenteron, in this case about a Milford, Letterkenny. fourth of the whole alimentary canal. The incurved portion of the tail was free from the annulus, and its growth seemed to be caused by the formation
SOME NEW DIATOMACEOUS FORMS of the dorsal half of the body carrying along the
FROM THE "SAUGSCHIEFER” OF ventral segments with it. In the tail this dorsal
DUBRAVICA. portion increased much in size beyond the ventral, both in length and thickness. Up till its full growth
By F. KITTON, Hon. F.R.M.S. the dorsal section of the abdomen had been without segmentation, but, in the afternoon of the 8th August, : U ERR GRUNOW in his “ Beiträge zur KentI observed it to be crenate externally ; and that the I niss der fossilen Diatomaceen Oesterreichindentations corresponded to the lines of division of Ungarn” (“ Beiträge zur paläontol. Oester-Ungarns. the ventral segments. That portion of the dorsum und d. Orients von Majsisovics u. Naumayr," Bd. extending beyond the venter and beyond the last ii. 1882), describes the following diatomaceous crenation opposite the last ventral segment, was deposits found in Hungary : (1) “Saugschiefer " much larger than any other division, and showed (absorbent slate) from Dubrávica ; (2) Polierschiefer itself a crenate division into three, of which the last, Tallya ; (3) the argillaceous tufa from Holaikluk; much narrower than the others, I supposed might (4) diatom deposit from Kis-ker; (5) Kieselguhre turn out to be the anal proleg, whilst the penult from Eger and Franzenbad in Bohemia. The last crenation would represent the anal flap. I thought named deposits are generally well known to Diaalso I could trace the posterior section of the tomists (particularly that found in Franzenbad). alimentary canal terminating in the space between Ehrenberg described many of the forms in the the anal flap (?) and the proleg (?) In the evening of “Monatsberichte" of the Royal Academy of Berlin, the same day I was able to distinguish four prolegs 1840, which are afterwards figured in his “Microon the anterior abdominal segments, near the point geologie.” His figures of Campylodiscus clypeus have of flexure, but could not see whether one or two been frequently copied. segments intervened between them and the thoracic The Hungarian deposits were almost, if not legs. On the 8th also, in the evening, the remote entirely, unknown until the recently published ingroup of eye-spots became dimly visible through the vestigations of Herr Grunow, which, unfortunately, transparent head. At first, directly opposite one are not readily accessible to Diatomists, excepting another, the two groups of eye-spots diverged more by the purchase of the volume of the work (at a cost and more till they came to be situated at the lateral of 40 marks) in which they appeared. Having borders of the head, and between, and rather in through the kindness of a correspondent been advance of them, a cupid's-bow-shaped line (Fig. 39) enabled to examine one of the most interesting of appeared to indicate the anterior border of the them, viz. that from Dubravica, I have identified clypeus. The direction of this torsion of the head most of the species named in the list which was always such that, whether the embryo was lying accompanied the sample. The deposit is someon the right or left side, its effect was to bring the what delusive ; from its general appearance we dorsal aspect of the head next the free unattached should suppose it would be easily cleaned ; but this side of the egg, and the under surface next the glass. is not the case; when boiled in acids the material
Unfortunately my observations were brought to an split up into thin laminæ of sufficient tenuity to untimely close by an accident on the morning of the allow of mounting without further manipulation; to 9th, so that the last stages, as well as the earlier, separate the diatoms a careful boil in dehydrated both of which should have much of interest to offer, soda is necessary to dissolve the silicic acid which escaped me. I believe, however, that what I have | cements the diatoms together. This cementation