

4 HUMAN SPERMATOGENESIS: A STUDY OF INHERITANCE. 



upon the Zenker's fluid material, for it seemed to show on the whole better 

 preservation than the other and exhibited the individual chromosomes much more 



distinctly; the chromosomes after use of the other fixations named appeared 

 much more swollen and frequently even agglomerated. Paraffine sections were 

 stained by the iron hsematoxyline method, usually followed by eosin, with 

 safranine, and, possible only upon Bouin's fluid material, with the Ehrlich- 

 Biondi-Heidenhain triple stain. A large number of slides were prepared and 

 each section carefully examined for mitoses, and in this way much time was 

 devoted simply to finding maturation mitoses. 



In a previous paper the history of the Sertoli cells was given by me. In 

 the present one the stages from the late growth period to the mature spermatozoa 

 will be treated. 



I. The Spermatocytes and their Divisions 



a. observations. 



1. Primary Spermatocytes. 



The greater number of spermatocytes do not exceed in size those shown in 

 figs. 2-25, PI. I. Rarely one finds amongst these small groups of much larger 

 primary spermatocytes, of which one is drawn in fig. 1. These giant spermato- 

 cytes are so seldom found that they should be considered abnormalities; and 

 the only one of them seen in division exhibited a large number of chromosomes 

 (more than 32). We will disregard these giant cells in the following account. 



It is sometimes difficult to distinguish sharply and positively primary from 

 secondary spermatocytes. Late growth period stages of the primary ones are 

 easily distinguished (figs. 2-6) , for they exhibit the strepsinema form of chromo- 

 somes so characteristic of corresponding cells in most animals. But to distinguish 

 the first from the second maturation division is often difficult. Volume of the 

 cell or nucleus alone is not always a sure criterion, for the spermatocytes vary 

 considerably in volume; position within the seminiferous tubule gives no clue, 

 for all spermatocytes lie near the axial lumen, only spermatogonia being at the 

 periphery. Also in both mitoses there appear to be two centrioles at each pole, 

 so that number of these offers no distinction. The surest criteria between 

 the primary and secondary spermatocytes is that in the former the chromo- 



t 



somes are larger and certain of them are more or less distinctly quadripartite 

 while in the secondary spermatocytes they are smaller and usually in the form 

 of distinct dyads. Also in the primary cells the spindles are usually relatively 

 longer. On account of these difficulties I cannot be certain that in all cases I 

 have correctly assigned the generation of a cell, but I believe I have done so in 

 the greater number. 



In the later growth period two kinds of bodies are usually to be found 



within the nuclei. First, generally two plasmosomes, (PL I, figs. 2-8, 11, 12); 



these are rounded and lie within the nuclear membrane. Parts of one or both 



