1890-91.] AMPHIBIA BLOOD STUDIES. 229 



to their relation to each other and to the importance of the questions 

 raised in these studies. 



The red cells measure 50 — 53/j'. in lengtli and 30 — 32// in breadth. In 

 the fresh and normal condition they present usually in nucleus and 

 disc a uniform yellow red tint; and in the disc a completely homo- 

 geneous discoplasma. There are sometimes corpuscles possessing 

 whitish nuclei which appear contrasted in this respect with the colored 

 disc, but these are not numerous until the preparation has been kept 

 under certain conditions, as in a moist stage, for some time. In such 

 nuclei one can determine the presence of a coarse network. The mem* 

 brane of the disc is very thin, so much so that when it is ruptured and 

 freed of its contents it is rarely visible. I have frequently, by artificial 

 means, ruptured a large number of the discs in a moist chamber and in 

 only a very few cases was I able to see the resulting free membranes, 

 although there were in such preparations an abundance of free nuclei. 

 The contents of the ruptured corpuscles have different fates. That of 

 the nucleus and of a portion of the protopla^^m I shall describe fully 

 when treating of the fusiform corpuscle. The haemoglobin and the 

 stroma containing it become dissolved in the serum, hardly leaving a 

 trace visible. This points to the fluid character of the discoplasma and 

 I now proceed to prove that view of its structure. 



If a cover-glass preparation of the blood is fixed with a saturated solu- 

 tion of corrosive sublimate, stained with haematoxylin and eosin, mounted 

 in balsam and studied with the best objectives at one's disposal, the 

 protoplasm of the disc will appear perfectly homogeneous and will be 

 seen stained uniformly and intensely by the eosin. Granules and 

 vacuoles are absent, and if the nuclear membrane is shrunken away from 

 the discoplasma, the edge of the latter next it will then appear regularly 

 and evenly outlined. Vapor of osmic acid fixes the discoplasma in 

 the same way that corrosive sublimate does. This brings out distincth' 

 the fact that there can be no natural separation of stroma and haemoglo- 

 bin in the discoplasma. In other words, we may say that the latter 

 is not homologous with the cytoplasma and enchylema of ordinarx- 

 cells, but that in the normal condition it is in the physiological sense 

 a single element. It is true that in certain methods of fixation the 

 protoplasm of the disc appears reticulated, and this may occur in a 

 few of the cells fixed by corrosive sublimate (Fig. i), but in every case 

 the fineness and arrangement of the reticular trabeculae depends on 

 the method of fixation, and this shows that the reticulum is artificially 

 produced. One has but to look at Figs, i, 2, 3, and 4 to see how the 

 artificial structure varies in character. The preparation of the blood 



