COMPARATIVE HISTOLOGY AND PHYSIOLOGY OF THE SPLEEN. 291 



is attached to a giant cell by a conical pedicle of protoplasm continuous with and 

 similar to the perinuclear protoplasm, which hyaline pedicle is contained within a 

 crevice of the granular protoplasm of the giant cell. Such a cell has all the characters 

 of an erythroblast. (2) Other cells more numerous than the ordinary giant cells 

 (perhaps a hundred in a section), have many isolated nuclei of different sizes, most, but not 

 all of which are contained within spaces that appear to be vacuoles ; a few seem to be 

 imbedded in the original granular protoplasm. Some of the nuclei in the vacuoles are 

 immediately surrounded by a rim of deeply pink-stained protoplasm. (Plate III. fig. 16.) 

 Frequently the vacuoles near the surface of the cells, perhaps three or four in each, 

 have no nuclei, and from other superficial vacuoles hyaline protoplasmic corpuscles 

 appear to be escaping. (3) Probably the most numerous of the special cells are those 

 consisting of a large number of nuclei, each of which is contained in a capsule-like 

 space or vacuole, and all of which are surrounded by a comparatively thin membrane 

 that consists of little if anything more than the outer portion of the wall of the outer- 

 most vacuoles. (Plate III. fig. 16.) In some cells there are as many as thirty nuclei, 

 each contained within a vacuole, and perhaps three or four of these have a rim of peri- 

 nuclear protoplasm. These special cells vary much in size ; their average measurement 

 is about 32 /u, by 38 jjl. The envacuoled nuclei likewise vary in size ; in some cells 

 they are nearly all of comparatively large size, measuring about 8 /x, in other cells they 

 are nearly all about half this size, but in most cells there are both large and small 

 nuclei. The larger nuclei that stain less deeply have sometimes the appearance of 

 karyokinetic change. (4) The fourth variety of the special cells consists of those in 

 which the empty vacuoles are far more numerous than those that contain nuclei ; 

 in some cells there are about twenty of the former and only two or three of the 

 latter. Many of these cells closely resemble the special vacuolated cells — the so- 

 called blood-corpuscle holding cells — in the spleen of the rodent animals. (Plate III. 

 %. 17.) 



In the spleen of a Human Foetus probably between the seventh and eighth month 

 there are a few similar multinucleated special cells which are not quite so large as 

 those in the later foetus ; their average size is about 16 by 20 /x, and three or four may 

 be found in a section. In the follicles are somewhat numerous coarsely granular 

 protoplasmic corpuscles. Scattered throughout the pulp are many nucleated red blood- 

 corpuscles, most of which appear to belong to the blood, but there are only a few 

 erythroblasts. 



In another foetal spleen at about the seventh month similar special multinucleated 

 cells occur in very small numbers ; and in slightly larger numbers the smaller vacuolated 

 special cells like those that are found in the spleens of the rodent animals, but there 

 are no characteristic giant cells. Eosinophilous cells are somewhat numerous ; nucleated 

 red blood-corpuscles are still more numerous, but erythroblasts are scarce. 



In the spleen of a fourth Human Foetus between the fourth and fifth month 

 there are a few somewhat small but otherwise characteristic giant cells, about four or 



