36 THOS. It. MONTGOMERt ji*., 



of these cells of follicles 1 and 3 is thus marked from the synapsis 

 stage on, and results in the formation of larger spermatids than are 

 found in the other follicles of the testicle (whence must be concluded 

 that the spermatozoa formed in follicles 1 and 3 are also larger). The 

 volume of the resting spermatocytes of the large generation is about 

 double that of those of the small (compare Figs. 99 and 100 with 

 Figs. 95 — 98). The great size of cells of the large generation is due 

 to increase in the mass of the idiozome substance and of the cytoplasm, 

 and corresponding increase in the size of the nucleus. But one sub- 

 stance is present in exactly the same amount in cells of both 

 generations, namely the chromatin, for notwithstanding their greater 

 size, the cells of the large generation have no more chromatin than 

 those of the small. Thus it is that the chromosomes of the reduction 

 divisions have the same dimensions in both generations, and therefore 

 the amount of chromatin allotted to the corresponding spermatozoa 

 must be the same. A comparison of the figures of the reduction 

 divisions of both kinds of spermatocytes, shows clearly that there can 

 be no difference in the amount of the chromatin in the two generations, 

 all chromosomes having been drawn with the camera lucida (compare, 

 on PI. 4, Figs. 167—169, with Figs. 172—175). Also in the rest and 

 telophase of cells of the large generation, the amount of the chromatin 

 appears to be no greater than in the small generation, their nuclei appearing 

 much clearer. The significance of this remarkable fact will be discussed 

 later. The greater size of the nuclei of the large generation is due to 

 greater amount of nuclear sap, possibly also to greater amount of linin. 

 As to the causes for the differentiation of two kinds of spermato- 

 cytes. The diff"erence in size first becomes apparent in the stage 

 of synapsis, i. e. at the commencement of the growth period. 

 Accordingly, the growth period being without doubt the period of most 

 rapid nutrition of the cells, the greater size of the cells in the follicles' 

 1 and 3 must be due to their receiving a greater amount of food 

 than those in follicles 2, 4, 5 and 6. That is to say, the follicles 1 

 and 3 must be nourished by a richer blood supply. I was unable to 

 find diff'erences in the connective tissue walls of the various follicles, 

 but since the blood must circulate through the lacunae of these walls, 

 future injection preparations might be of value in determining this 

 point. Blood fluid is demonstrated within each follicle, in the spaces 

 separating the spermatocytes, by a homogeneous substance which 

 becomes stained a light brown by the action of Hermann's fixative; 

 there is no possibility of confounding this substance with the Mater's 



