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these bodies present to vegetable structures—a resemblance such that they have been regarded, now rather as real starch, now rather as analogous to cellulose. The next organ I came across, although there is no close resemblance in external appearance between it and the ependyma, was the spleen and indeed a condition of it, in which its follicles were wholly converted into this translucent, waxy matter (sagoey spleen—Sagomilz). Soon afterwards Meckel published his well-known observations which demonstrated the occurrence of this substance in several places, but especially in the kidneys, the liver and the bowels, and we afterwards succeeded in finding it in different other parts, in the lymphatic glands, throughout the whole of the digestive tract, in the mucous membranes of the urinary passages, and finally even in the substance of the muscular organs—the heart, and the uterus—aswell as in the interior of cartilages— so that at the present moment there are but few parts of the body that we do not know may undergo this peculiar change. If we investigate the matter more closely, it seems that two allied, but not identical, substances must be distinguished. In the first place we find bodies which in their chemical properties are more analogous to real vegetable starch, and in form too bear an extraordinary resemblance to vegetable starch-granules, inasmuch as they constitute more or less round, or oval structures, formed by a succession of concentric layers. To this class belong, above all, the corpora amylacea of the nervous system (Fig. 94). Many of the laminated amyloid bodies are of very large size; their diameter may become so considerable, that they may be very distinctly recognized with the naked eye. To this category belong, in particular, a part of the laminated bodies, that are found in the prostate of every adult man and under certain circumstances accumulate in large quantities, so as to form the so-called prostatic concretions; and also rare forms of a similar kind which have been shewn by Friedreich to occur in several conditions of the lungs.

These formations vary in size from very small, simple, homogeneous looking structures up to gigantic bodies, in which, when they are regularly formed, we see a succession of very numerous layers. Just as the small amyloid corpuscles of the nervous system are frequently composed of two separate ones and constitute twin structures, it very frequently happens here also, that a common envelope encloses separate centres (Fig. 120, d, e). Nay, in isolated cases this goes on to such an extent, that whole heaps of smaller bodies are held

Eio. 120.


together by larger common layers. These very large, though certainly more rare, forms may attain a diameter of two lines, so that they can easily be isolated from the tissue in which they lie, and be subjected to examination even with the naked eye. There seems to be scarcely any doubt, but that in these cases a substance is set free, which gradually adheres to the outside of pre-existing bodies all

Fig. 120. Laminated prostatic amyloid bodies (concretions); a, oblong, pale, homogeneous corpuscle, with a nucleus-like body. b. A larger, laminated corpuscle with pale centre, c. A still larger corpuscle with several layers and a coloured centre, d, e. Bodies with two and three centres, in d of a deeper colour. /. Large concretion with a dark-brown, large centre. Magnified 300 diameters.


round, and that therefore we have not here to deal with the degeneration of a definite tissue, but with a kind of separation and precipitation, such as we see occur in the case of other concretions from fluids. It may, with some probability be concluded, that the prostate, through the dissolution of its elements, furnishes a fluid which, by the gradual formation of deposits, produces these particular forms.

Now the peculiarity of these structures is, that by the simple action of iodine they very frequently assume just as blue a colour as vegetable starch does. According as the substance is more or less pure, its colour changes, so that when, for example, there is much albuminous matter mixed up with it, it becomes green instead of blue; for the nitrogenous substance is rendered yellow by iodine, and the amyloid blue, so that the whole effect produced is green. The greater the quantity of nitrogenous matter, the browner does the colour become, and not unfrequently do we find, side by side in the prostate, concretions, which, after the application of the iodine, present the most varied colours. So far these formations are distinguished from those little amylaceous corpuscles of the nervous system, which, one and all, assume a blue or bluish grey colour on the addition of iodine. It must also be remarked, that many prostatic bodies, though quite analogous in their structure, only become yellow or brown upon the addition of iodine, and consequently differ in chemical constitution.

Essentially different from this separation of starch-like matter, which lies between the elements, are the degenerations of the tissues themselves, in which all their constituents (parenchyma and interstitial tissue), as such, become directly filled with a substance also of an amyloid nature, and are gradually infiltrated with it just as tissues become infiltrated with lime in calcification. No two things can be more justly compared than calcification and the amyloid change (lignification). This (amyloid) substance, which produces the real degeneration of the tissue, exhibits the peculiarity, that it never becomes blue under the influence of iodine alone. At least no case is as yet known, in which the substance has yielded this colour with iodine in the parenchyma of tissues. On the contrary, a peculiar yellowish red colour is seen to arise, which it is true in many cases has a slight tinge of reddish violet, so that a certain approximation is manifested to the blue of real starchy matter. On the other hand, it displays pretty regularly a real, either perfectly blue, or violet colour, when the application of iodine is followed by the very cautious addition of sulphuric acid. A certain degree of practice indeed is requisite; the exact proportion must be hit upon, inasmuch as the sulphuric acid generally destroys the substance very quickly, and either very indistinct colorations are obtained, or the colour manifests itself only for a moment, and then immediately disappears again. Thus this substance is less nearly allied to starch properly socalled and more akin to cellulose, as I have already described it (p. 5). But from cellulose again it is also distinguished by the fact of its becoming coloured upon the application of a pure solution of iodine, whilst real cellulose is not at all coloured by iodine alone. Cellulose behaves precisely like cholestearine which remains colourless when treated with iodine, but on the other hand assumes a blue, or under certain circumstances a red, or orange colour upon the addition of iodine and sulphuric acid (p. 358).

Owing to this multiplicity of reactions it is really still very difficult to say with certainty to what class the substance belongs. Meckel has followed up the idea with great care, that we have to deal with a kind of fat which is more or less identical with cholestearine; but we are as yet unacquainted with any kind of fat which combines in itself the three qualities of becoming coloured upon the addition of iodine alone, of remaining colourless upon the


addition of sulphuric acid alone, and of assuming a blue colour when acted upon by iodine and sulphuric acid. Besides the substance itself does not in any way behave like a fatty matter; it does not possess the solubility which characterizes fat; and in particular no substance can be obtained from these parts by extraction with alcohol and ether, which possesses the peculiarities of the original one. According to all this there is rather a correspondence with vegetable forms, and the view may still be maintained, that we have here to deal with a process comparable to that which we see set in during the development of a plant, when the simple cell becomes invested with capsular layers, and gradually grows woody.1

These changes can be best followed in those structures which must on the whole be regarded as the most frequent and the earliest seat of this change, namely the smallest arteries. These first undergo the transformation, and only after the constitution of their walls has become changed,

1 The analyses of amyloid spleens recently made by Kekulc and Carl Schmidt have yielded such a large proportion of Nitrogen, that both these chemists have come to the conclusion that the amyloid substance is of an albuminous nature. We know, however, from experience, that the results furnished by these analyses of whole organs are very little to be depended upon, so little indeed, that no chemist was ever able to infer from any analysis he had made of the liver, that it was rich in Glycogen. Only when we have discovered the means of isolating the amyloid substance, shall we be able to come to any definite conclusion with regard to its nature.

To Schmidt's analyses of the corpora amylacea of the brain we cannot attach the slightest importance, because his statements concerning them were founded upon an error. He says, namely, he selected for his analysis a choroid plexus (from a human brain) rich in corpora amylacea. But corpora amylacea are never found in large numbers in these plexuses—indeed it seems to me doubtful whether they are ever farmed there. The concentric corpuscles which Schmidt examined were therefore probably those sabulous bodies (Sandkorper—acervulus cerebri, brain-sand) which are nearly always present in the choroid plexuses and so greatly resemble the corpora amylacea in structure, that they were actually taken by Kemak to be such. Schmidt, thinking he had the same substance before him in the spleen, published his two analyses with the idea that he was thereby furnishing a doubly strong proof of the albuminous nature of this animal amyloid substance.—From a MS. note by the Author.

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