178 Harry Lewis Wieman. 



which contains only cell fragments. These fragments are the 

 remains of the more solid parts of the cells, the liquid constituents 

 having been separated and secreted into the general cavity of the 

 testis where they probably serve as a nutrient medium for the 

 spermatozoa. This is suggested by the fact that the cavity of 

 the testis is at first occupied by the degenerated area, and as the 

 latter retreats toward the distal end of the testis, the former 

 gradually comes into existence as the continuation of the lumen 

 of the sperm duct. As a result then of the process of contraction, 

 the fluid contents of the degenerated area would be expressed 

 into the central cavity of the testis. The degenerated area might 

 of course be regarded as a general source of nutrition for the germ 

 cells in all stages of development, instead of merely the mature 

 spermatoza. 



The degeneration then may be of significance in connection 

 with nutritive processes; but it is to be remembered that the cells 

 involved are not homologous with the nurse cells of the ovary, 

 since the latter are derived from the primordial germ cells. This 

 is not necessarily an objection, but is only in accordance with 

 what might be expected. The spermatozoa are produced in far 

 greater numbers than the ova. In order for this to happen it 

 is essential that all or nearly all of the germ cells of the male 

 develop into functional spermatozoa, none, if any being reserved 

 for the function of supplying nutrition. That would throw this 

 function on the only other element of the testis, namely, the 

 epithelial cells. In the ovary where the course of evolution has 

 taken a different trend, a large number of relatively small and 

 simple ova has come to be not so essential as a small number of 

 greatly enlarged and highly complex germ cells, as a result of 

 which a considerable number of non-functional germ cells become 

 the nurse cells of the ovary. 



III. The Chromosomes 



The chromosomes of L. signaticolKs are not of a size and number 

 to make the material the best for a satisfactory study of all stages 

 of the maturation process, but they present a number of features 



