380 S. SAGUCHI 



them; still there are cases where this does not hold. Zymogen 

 granules, even when they are densely packed together in the cell- 

 body so that the nucleus is compressed against the base, can 

 never be seen between the nucleus and the basement membrane 

 (figs. 39, 44, 61). Above the nucleus there is usually a light 

 area in which zymogen granules either are wanting or are pres- 

 ent in small numbers; in other cases, it contains smaller granules, 

 yet it is well marked off from the remaining portion by a clear 

 zone (figs. 61, 75, 76, 78, 81). It can often be seen that the 

 area is subdivided by clear stripes into a number of parts, so that 

 it exhibits a reticular appearance. This area is usually situated 

 immediately above the nucleus, or more or less apart from the 

 latter; it is very seldom situated nearer the cell-periphery than 

 the nucleus. I shall return to this area a little later when the 

 genesis of zymogen granules is considered. 



Zymogen granules exhibit a little variation in size, which indi- 

 cates that they have a definite limit of growth and are well indi- 

 vidualized so that they do not flow together as such. On the 

 other hand, we cannot find such small granules as coincide in 

 diameter with the mitochondrial filament, at least not in mito- 

 chondria preparations (figs. 39, 44, 55) in which some believe to 

 have found small granules, which according to them, must grow 

 up to zymogen granules. 



Macallum ('91) admits that zymogen granules present next to 

 the lumen are larger than those near the nucleus, since they in- 

 crease in size during their passage toward the lumen by the depo- 

 sition of a certain substance derived from the protoplasmic area 

 of the cell; Mathews ('99), on the contrary, describes the gran- 

 ules next to the nucleus as always larger. So far as can be seen 

 from my preparations, there are no such relations between the 

 sizes of zymogen granules and their positions. I have also no- 

 ticed that the periphery of the granules is more deeply stained 

 than the center, but not to such an extent as to lead to the forma- 

 tion of 'crescent-shaped corpuscles,' as pointed out by M. Heiden- 

 hain ('90) in the pelvic gland of the triton. 



3. Genesis. Historical. Regarding the origin of secretion 

 granules in general, there is full discussion in the papers of 



