408 E. L. SHAFFER. 







tioned, was the most satisfactory. In Hermann and Benda 

 material there is a tendency, especially in the spermatocytes, 

 for the mitochondria to agglutinate in dense irregular masses. 



C. OBSERVATIONS. 



(a) Chromosomes. 



Although not primarily concerned with the chromosomes in 

 the present report, it may be of some interest to at least mention 

 these in a general way. I have as yet been unable to find sperm- 

 atogonial plates of sufficient clearness to make accurate draw- 

 ings, but all counts indicate that the chromosome number is 26, 

 including an unequal pair. This has been confirmed by a study 

 of the ovaries in which all dividing follicle cells show 26 chromo- 

 somes and these can be arranged in equal pairs (Fig. 3). The 

 metaphase plate of the first spermatocyte (Figs. 12, 33) shows 

 13 bivalent chromosomes, one of which represents the unequal 

 (sex) pair. The elements of the sex pair separate in the first 

 maturation division and divide equationally in the second 

 division. 



(b) Mitochondria. 



I shall not attempt to review the vast literature which has 

 grown up bearing on the subject of the mitochondria. Dues- 

 berg ('n) has given a rather complete review of the literature, 

 so that it will not be necessary to do so here. I shall, however, 

 discuss the works of others insofar as these may be related to 

 my observations on Passalus. 



i. Spermatogonia. In the primary spermatogonia, which are 

 situated at the blind end of the testes, I have been unable to find 

 conclusive evidence of the presence of mitochondria (Fig. i). 

 The cytoplasm is usually of a homogeneous, non-reticular and 

 finely granular structure. These granules do not stain in any- 

 thing but the plasma stain, and therefore cannot be considered 

 as mitochondria. There are usually present, in the cytoplasm, 

 several deeply staining bodies (hsematoxylin) which are per- 

 haps similar to the chromatoid corpuscles of other workers. It is 

 possible that these may really be of a mitochondrial nature, but 

 their subsequent fate cannot in any way be related to the mito- 

 chondria of the later stages. Lewis and Robertson (1916) in 



