we melt it, and allow it to cool to about 100°, and then, while it is still soft and viscid, we rapidly and frequently extend and double it up. The temperature of the mass quickly rises to 140° or upwards, and after this evolution of heat the sugar is found on cooling to be in the condition, not of a glass, but of minute crystals.

Phosphorus is another substance which is susceptible of a somewhat similar change. At ordinary temperatures it is a clear, colourless body, which melts into a liquid when heated to about 113° F., and readily catches fire at comparatively low temperatures when exposed to the air. In an atmosphere of a gas with which it does not combine, it may however be heated to a temperature of 460° or higher, and then the translucent liquid phosphorus forms a red deposit, which is nothing else than another modification of phosphorus.

This allotropic phosphorus, as it is called, may also be prepared by dissolving ordinary phosphorus in bisulphide of carbon along with a small quantity of iodine, and heating the solution to 212° in a sealed tube for some time. The red phosphorus is then precipitated from the solution in proportion as it is formed.

The difference in the appearance of the two modifications of phosphorus is obvious. They are known to differ also in most of their properties; thus they are not soluble in the same menstrua; the liquids which will dissolve one generally failing to dissolve the other. The density of ordinary phosphorus is 1-83, while that of the red modification is 2.1; the temperatures at which they respectively ignite are also very widely separated. Notwithstanding all these and other differences betweeu them, they are mutually convertible. The red variety is prepared from ordinary phosphorus, and may be converted into the latter again by simply heating it to the temperature at which it evaporates, and condensing the vapour. Their properties are in many respects less alike than those of gold and platinum; yet we do not hesitate to pronounce the substance of both identical. What then causes the difference?

In the case of phosphorus, and several other bodies which are susceptible of similar changes, we have not far to seek for the answer. The difference in the properties of the ordinary and of the allotropic modifications of phosphorus, is due to the different quantities of heat that are present in a latent form in the one and in the other. It is not usual to speak of heat as a constituent of bodies, but there can be nothing better established than that its presence is the modifying element in these cases. I might give many proofs of this, but it may be sufficient to mention that in the preparations of red phosphorus by the action of iodine, Brodie found that on heating the mixture of ordinary phosphorus and iodine to 390°, a sharp explosion took place, with a loud report, while nearly the whole of the

phosphorus used was found to have passed into the allotropic or red modification. In short, ordinary phosphorus in passing into the red condition sets free its combined heat, which then becomes sensible.

Among bodies derived from the organic world there is a group, known as the glycerine compounds, of the series of acids to which formic, acetic, and other acids of the general type (CH2)O2 belong. I know that several, and I believe that all, of the glycerine compounds of these acids, as met with in nature, are susceptible of different allotropic modifications, such as those we have been speaking of. Chemistry is familiar with some twenty of these acids, and upon good grounds presumes the existence of a great many more of them. In the whole domain of modern chemistry there is no group of bodies equal to these acids, and their connections, for interest and instruction. It were out of the scope of my present remarks, however, to enter upon a discussion of their chemical relations generally, but I may just mention that corresponding to each of the acids of this series there are an alcohol, an ether, an aldehyde, and other bodies, each of which bears a definite relation, as represented by its chemical constitution, to the corresponding terms (isologues) of all the other series. This is readily seen from the following formulæ of a few isologous terms of three of the series :

modern chemistry has advanced her frontier farthest, and effected her greatest conquests in the investigation of the constitution of matter.

As I have already indicated, the particular series of this group of substances to which I have to direct attention in connection with pleomorphism, consists of those fats-such as margarine, palmatine, and stearine-which, when decomposed by an alkali, yield an acid of the series in question, and glycerine. It is a very remarkable fact that there are many glycerine compounds of fatty acids which consist of carbon, hydrogen, and oxygen; but, so far as I know, it is only those the acid of which belongs to the particular type (CnH2) O that have the capacity of assuming different physical conditions; thus oleine, which is perhaps a constant accompaniment of stearine, palmatine, &c., in nature, and which differs in composition very little indeed from the type of these bodies, appears to be destitute of the capacity of assuming the allotropic conditions which are known to belong to those bodies. I have here specimens of these different substances-stearine, palmatine, margarine, and oleine; but it will be sufficient for our purpose to describe the phenomenon in question as manifested by stearine. Now stearine in the purest condition in which it has been prepared is at ordinary temperatures a solid substance, which, when heated to 125° F. melts, and then, if kept at that or a slightly higher temperature, resolidifies; after this resolidification it melts only when the temperature is raised to 147°, and now solidifies again at a temperature slightly above this melting-point; but after this last solidification it melts only when the temperature rises to 157°. After this melting, however, it refuses to solidify at any temperature higher than the melting-point we began with— viz. 1253°. In other words, it has three different points of fusion: it melts at the temperature of the first, solidifies: melts at the temperature of the second,-solidifies; melts at the temperature of the third, and then solidifies only when the temperature falls below all three points of fusion; and, after solidifying here it may be made to melt again at the first, at the second, and at the third meltingpoints respectively, solidifying, as before below all three; and these changes are reproducible in this order of succession to any extent without the slightest loss or gain of weight. Are we to say that these different melting-points belong to one and the same substance, or to three different substances? Undoubtedly they belong to one and the same sub. stance, but to three different modifications of it. These modifieations differ from one another, not only in melting-point, but in several other respects: -the first modification, or that which is formed when the substance solidifies at the lowest of the three melting-points, is amorphous,--it is destitute of all structure whatever; the third is crystalline in

-

structure, and is, in fact, identical in all respects with the crystals deposited from a solution of stearine in ether: the properties of the second modification are intermediate between those of the other two. They are distinguishable, also, by their density, as may be seen by those specimens of the first modification floating, while the other two sink in water. What I have said of this phenomenon as manifested by stearine, holds good of it, with very slight modification, in the case of each of the other analogous substances, palmatine, margarine, &c. (To be continued.)

ON A PARASITIC WORM INFESTING A MARINE FISH.

N April, 1874, my friend Mr. W. R. Hughes,

F.L.S., sent me a fine specimen of the smaller Wrasses, the Crenilabrus rupestris, or "Goldswing," which had been kept in his marine tank in company with several others. It had fed well and thrived in confinement (its food consisting of smelt and other white-fleshed fish), until about a week before it died, when it showed an inability to keep in the horizontal posture, and died apparently exhausted. I received it the next day, with a note from Mr. Hughes giving the above particulars, and asking for a post-mortem examination, which was made at once, with the following results.

External appearances.-There was a fulness about the ventral surface which made me suppose that the fish died consequent upon its inability to deposit spawn; but, as the examination showed, this idea was erroneous, as the fish was an adult male. Mr. Hughes told me the next day that he had held the same opinion whilst the fish was_moribund, and had sent it to me for confirmation. An appearance of inflammation was observed extending upwards and around the anal orifice, but no other external indications of the cause of death were noticeable. The mouth, tongue, eyes, fins, and scales were healthy.

Internal appearances.-The viscera were all normal in their position, and apparently healthy. The red streak seen on external examination as extending inwards from and around the anal orifice, was evidently due to post-mortem changes. The heart and great blood-vessels, gills, œsophagus, stomach, liver, woolfian bodies, spleen, mesentery, lower alimentary canal, and air-bladder, were apparently healthy. Post-mortem staining was evident in nearly all these organs. The brain was well-developed and healthy, with but little change or staining. There was apparently nothing to be seen by the unaided eye which would account for death. Whilst turning them over with the point of a narrowbladed scalpel, I discovered a movement amongst the fibres of the connective tissue, which holds the organs in position. With a watchmaker's eye-lens

worms. Fig. 3 gives a good general idea of their form. Taking the liver by itself, I pressed it well between two slides, and found several of the parasites. All the other organs were examined in the same way, and, with the exception of the airbladder, all of them contained the worm in abundance.

Remarks.-These worms appear to be identical with the genus Prosthecosacter, as described by Professor Cobbold, and I feel inclined to believe that they agree with Prosthecosacter minor. I could

Fig. 6. Anal orifice of parasitic worm.

sometimes assuming a convoluted appearance, and had an anal orifice situated in the centre of the end of the tail, as seen in fig. 6, where the contents of the rectal end are seen to be extended. In this figure may be seen a fine corrugated line running down on the outside of the alimentary canal, which I suppose is one of the canals of the water vascular system.

This short description of a hæmatoid worm inhabiting, and no doubt killing the host, is of some little interest, because of the vast consumption of marine fish as food by the public, who as a rule are

not informed of the danger accruing to those who eat their fish half cooked. The eggs, or even encysted young, of parasitic worms are thus left undestroyed, and only waiting to be introduced into the alimentary canal of some highly organized animal as man to complete their development. WM. WRIGHT WILSON, F.L.S., &c.

I

Birmingham.

THE CHAT AND OTHER BIRDS: A
SUMMER'S STUDY.

BY CHARLES C. ABBOTT, M.D.

FIRST saw the Chat, last year, on Sunday, May 9th. From the topmost branch of a tall locust he sailed upwards and outwards for a yard or more, with fluttering wings and dangling legs, uttering a few harsh squeaks, and then alighting, warbling a sweet series of liquid notes, followed in turn by the yelping bark of a puppy, the squeak of a squirrel, or dull creaking of a rusty sign-board. Then, hopping from twig to twig searching for insects, he added his own peculiar chirp, alternated with low yet distinct notes, quite indescribable, but all hollow, ghost-like, gloomy cries. These weird, mournful groans, plaintive calls, and cries as of some poor creature in distress, would follow each other in quick succession; then, suddenly ceasing, an outburst of glorious melody would complete the strange series, and the restless bird, having regained his perch upon the topmost branch, would remain quiet for a moment, and then, with the same awkward, crooked flight, repeat the same series of strange and sweet notes, with some little variation, omitting some and adding other mimicry of uncouth sounds.

While I listened, wondering what strange sound would next greet my ears, I was surprised, even startled, by hearing them repeated, but at some distance off. Another Chat, farther down the path, is singing in the same strange way. Another it must be; for the one first heard is still in sight on the locust, flitting carelessly about, but apparently silent. Curious to hear the new-comer, I passed on, when the sounds were heard in the opposite direction. I retraced my steps, and now the strange medley came from the low bushes about me, and I looked carefully for the unseen Chat that seemed so near, when again, from the locust overhead, the series of odd sounds and sweet warblings came floating down to me.

The truth was now clear, the one bird had uttered every sound I heard, and, by his ventriloquism, had for the time completely deceived me. My study of this habit and its use now commenced, and for long weeks I watched him, to test, in every way, his

ability to mislead one by the exercise of this peculiar power. On the 13th a second Chat appeared, and the two (for it was a female) quickly selected a suitable site for the purpose, and, in a tangled mass of blackberry briars at the foot of the tall locust, they soon built a commodious but roughly-constructed nest. While his mate was sitting, the male Chat seemed more animated than ever, and, jealous of every intruder, threw his voice" in every direction other than towards the nest, if they came too near. On concealing myself, and getting very ncar, I found, by watching for an hour or more at a time, that when undisturbed they uttered fewer of the cries of other creatures, and seldom exercised their ventriloquial powers. Their song was varied and, at times, grand; but usually the cheerful notes were so intermingled with hollow, sepulchral tones as to render the entire utterance far from pleasing. It could never be so startled as to simply give a quick chirp of alarm and fly off. However suddenly I appeared from my concealment, there was an equally quick uttering of notes of distress such as I have described, coming, it seemed, from a point several yards distant. Vary my experiments as I would, it mattered not: the bird was thoroughly conscious of its ventriloquial power, and trusted far more to it than to flight to avoid and mislead its enemies.

How came this bird to possess so unusual a power? I will leave it to others to determine, making but a single suggestion with reference to it. Having closely observed the habits of a pair of these birds during the entire summer, I learned that the habit is one eminently useful to the bird, and, I think, possessed by the male only. This I could not positively determine.

When it is recollected that many of our birdsnotably the Mocker (Mimus polyglottus) and Catbird (Galeoscoptes carolinensis)—mimic not only the notes of other songsters, but sounds of almost every description, and that many gregarious birds post sentinels to give alarm on the approach of an enemy, it will be seen that the vocal powers of birds are not simply brought into play for their own satisfaction or that of their mates. During the lapse of ages, they have learned, through experience, something of the laws of sound, and know fully as well as man does that a loud note can be heard at a greater distance than one lowly murmured; for birds, when giving an alarm-cry, utter the note much louder than their ordinary chirps or song, which fact abundantly demonstrates the truth of my assertion. This knowledge of sound, simple as it is, is the starting-point for the acquirement, first, of mimicry, which is the intermediate stage of acquirement between ordinary vocal utterances, including songs, and that ventriloquial power which we have seen is possessed by the Chat.

Now, as this bird imitates very many sounds, it