290 DR A. J. WHITING ON THE 



seem to become frayed out and are applied to the walls of the venous sinuses as layers of 

 long, characteristically spindle-shaped fibres running in the long axis of the sinuses and 

 nearly parallel to each other in the one layer that belongs to each sinus. In transverse 

 section these fibres appear as irregularly pyramidal blocks, of a deep red colour after 

 staining with eosine, some of which contain a nucleus ; they are planted by their 

 bases upon what appears to be a connective tissue basement membrane, and thus form 

 a more or less nearly complete ring next the blood stream and are uncovered by endo- 

 thelium. It follows that the venous channels, along their whole course, have a close 

 relation with the muscular fibres of the trabecule. Some, at least, of these fibres appear 

 to terminate in the supporting cells of the stroma. Their appearance in longitudinal 

 view resembles that described by Frey as due to endothelial cells, and in transverse view 

 seems to be like that described as barrel-hoop shaped rings of elastic tissue. (Plate III. 

 fig. 16.) 



Four examples of the human fcetal spleen were examined, three of the child and one 

 spleen of a healthy adult. 



In the spleen of the Foetus between the eighth and ninth month the cellular elements 

 of the pulp are primarily of three kinds : — Lymphoid cells, protoplasmic corpuscles, and 

 giant or special cells. The lymphoid cells are chiefly uninucleated leucocytes, and are 

 comparatively sparse. The protoplasmic corpuscles are of four kinds : — (1) Smaller 

 hyaline protoplasmic cells, consisting of a deeply stained round nucleus, that possesses a 

 well-developed intranuclear network and measures about 5 \i in diameter, which is 

 surrounded by a comparatively narrow rim of yellow hyaline protoplasm that stains 

 deeply pink with eosine. These are the nucleated red blood-corpuscles. (2) Larger 

 hyaline protoplasmic corpuscles resembling the nucleated red corpuscles, but having a 

 relatively wider rim of perinuclear protoplasm. Their nucleus usually stains a little less 

 deeply, and like that of the smaller cells has no nucleolus. The diameter of the cells 

 measures about 8-10 ju,, that of the nuclei about 6-7 m- These are the erytkro- 

 blasts of Lowitt. (3) Eosinophilous cells are comparatively numerous. (4) Coarsely 

 granular protoplasmic corpuscles occur plentifully both in the pulp and in the follicles. 

 Their protoplasm stains very deeply with eosine ; they have usually only one nucleus, 

 but occasionally two or three ; they may or may not possess vacuoles. Some at least of 

 them seem to be young giant cells. 



Among the special cells there appear to be intermediate forms between the ordinary 

 giant cells, as found in the spleens of the lower animals, and the smaller special vacuo- 

 lated cells, as found in the spleens of the rodent animals ; these special cells are of 

 four main varieties : — (l) There are a few characteristic giant cells, perhaps three or 

 four in a section, which measure on an average about 30 n by 20 m. (Plate III. fig. 

 15.) Occasionally some of the nuclei are about twice as large as the others and are 

 less deeply stained ; these are usually near the middle of the cell, while the smaller 

 more deeply stained nuclei are near the periphery ; the latter measure from 4-6 v-. 

 Sometimes a deeply stained nucleus, surrounded by a narrow rim of hyaline protoplasm, 



