STRUCTURE OF COLORED BLOOD- CORPUSCLES. 85 



of the presence of a membrane, whether preexistent or artificially produced." 

 In fresh blood of amphiuma he has observed colored blood-corpuscles with a 

 greenish border, indicating ' ' the existence of a thin layer at the surface, dif- 

 fering, if not in chemical composition at least in density, from the substance 

 of the disks." He has frequently met with "specimens of blood-corpuscles, 

 on which, by a contraction of the protoplasm representing the greater portion 

 of the whole body, the pellicle in question appears separated from the latter." 

 Once he saw a fragment of a corpuscle on which " the membraneous layer was 

 seen projecting on the torn surface " ; and at another time he found " a fresh 

 blood-corpuscle of the amphiuma on which the membraneous layer had appar- 

 ently burst and retracted, leaving a portion of the underlying material, the 

 protoplasm, exposed." He says: "The changes taking place in these blood- 

 corpuscles, when treated with the solution of the hydrate of chloral, are very 

 interesting and important; as they manifestly show the existence of the mem- 

 braneous layer of these bodies, such as I have described it. Thus, after the 

 solution has been applied, the protoplasm of the blood-corpuscle, without 

 much or any alteration of form, gradually contracts upon the nucleus. As the 

 result of this contraction, it becomes entirely separated from the membraneous 

 layer, which manifests itself in the form of a delicate double contour. The inter- 

 space left between the contracted protoplasm and the double contour repre- 

 senting the membraneous layer is very considerable, as will be seen from the 

 drawings, and, it seems to me, should be sufficient evidence to prove the 

 existence of such a layer to an unbiased mind." In the colored blood- 

 corpuscles of the frog, he has also seen a distinct stratum, or membraneous 

 layer. 



" The colored blood-corpuscles of man show a double contour under vari- 

 ous circumstances and conditions, indicating the existence, if not of an 

 enveloping membrane, at least of a membraneous layer on its surface." As 

 one proof, Schmidt recommends the experiment of pressing down, by means 

 of the point of a forceps, a small round covering-glass upon a very small drop 

 of fresh human blood placed upon the slide, " with the object of compressing 

 or crushing the blood-corpuscles as far as possible." " Carefully examined 

 with a first-class objective of sufficient amplification, it will be found that they 

 have not run into each other; but that, on the contrary, the outlines of 

 almost every individual may be discerned, however distorted they may be." 



Almost all investigators nowadays agree that the colored blood-corpuscles of 

 birds, reptiles, amphibia and fishes have a nucleus ; while in those of man and 

 other mammalia, except in developmental forms, a; nucleus does not occur. 

 On this difference, Gulliver has founded his division of all vertebrate animals 

 into pyrenaemata and apyrenaamata.* But the existence of a nucleus in 

 living corpuscles of oviparous vertebrata has been denied on the one hand ; 

 while, on the other, the opinion has been advanced that the mammalian red 

 corpuscles, as well as those of other vertebrata, are in reality nucleated. 



Proceedings, with other Microscopical Intelligence. London, vol. i., No. 2 (May, 1878), pp. 

 57-78; No. 3 (July, 1878), pp. 67-120. 



* " Lectures on the Blood of Vertebrata," I. c. ; in Journal of Anatomy and Physiology, 

 vol. ii. ; Proceedings of the Zoological Society of February 25, 1862 ; and Hunterian Oration, 

 1863, referred to in " Observations on the sizes and shapes of the red corpuscles of the blood 

 of vertebrates, with drawings of them to a uniform scale, and extended and revised tables of 

 measurement." Proceedings of the Zoological Society of London, for the year 1875, Part ill., 

 p. 479. 



