COMPARATIVE HISTOLOGY AND PHYSIOLOGY OF THE SPLEEN. 285 



(2) small hyaline protoplasmic corpuscles, many if not all of which are erythroblasts ; and 



(3) giant cells. 



The protoplasmic corpuscles are numerous, occurring both around the giant cells 

 and generally throughout the pulp ; they have the usual characters of erythroblasts, 

 a round nucleus with a pronounced intranuclear network and diffuse chromatin, but 

 with no nucleolus, and a more or less narrow rim of perinuclear protoplasm, which is 

 hyaline, of a yellow tint, and which stains very deeply with eosine. Around the giant 

 cells and within the veins are similar but smaller cells, in which the nucleus of the 

 erythroblasts seems to have become condensed, so that it is relatively and absolutely 

 smaller and much more deeply stained : these cells are the ordinary nucleated red blood- 

 corpuscles. There are appearances of karyokinesis in the nuclei of the erythroblasts. 



The giant cells resemble those found in other spleens, but they vary more in size 

 and are on the whole smaller ; while the larger measure about 30 ju, by 18 fi, the smaller 

 measure about 18 /a by 10 ju,. Most of the smaller have a single, somewhat large, oval 

 nucleus, and some contain a relatively large number of vacuoles. They are all much 

 lobed and their nuclei show active budding. Frequently they appear to be broken up, 

 so that each isolated nucleus has a covering of protoplasm and forms a separate cell, 

 while a considerable part of the protoplasm is apparently left without any nucleus. 

 Giant cells are not unfrequently seen within the lumen of the veins. 



In the spleen of the Namvhal the majority of the cells are round protoplasmic 

 corpuscles, consisting of a large round nucleus, that has a well-developed intra- 

 nuclear network but no nucleolus, which is surrounded by a rim of hyaline yellowish 

 protoplasm that stains of a reddish-brown colour with eosine. These cells are 

 almost certainly erythroblasts; they measure about 10 /a in diameter and their 

 nucleus about 8 ju,. The perinuclear rim of some cells is filled with coarse round 

 granules that stain deeply with eosine. There are similar smaller cells, whose 

 nuclei stain very deeply, and which possess a slightly broader rim of perinuclear proto- 

 plasm ; these are almost undoubtedly nucleated red blood-corpuscles. Both kinds of 

 cells are found in the veins. Giant cells are present in considerable numbers ; the 

 smaller consist of a much lobed nucleus or central heap of nuclei surrounded by a rim 

 of hyaline yellow protoplasm ; the larger show more pronounced budding of the 

 nucleus. Sometimes a cell resembling the erythroblasts is contained within the 

 substance of the cell near its periphery (as was described in the spleen of the puppy), 

 and similar cells are clustered in numbers around the giant cell, many of them being 

 in apposition with it and contained in cavities on its surface. The nuclei of the giant 

 cells are sometimes completely separated from each other, and there is an appearance, 

 similar to that described in the spleen of the porpoise, as if the giant cell were breaking 

 up to set them free. 



In the spleen of the Rabbit the reticulum of the pulp varies little from that of the 

 dog ; the cells forming it are more numerous in a similar sectional area, and are more 

 delicate. They are typically stellate, their nuclei are often large, oval, and stain faintly 



VOL. XXXVIII. PART II. (NO. 8). 2 Q 



