SPERMATOGENESIS OF ASCARIS 423 
found some that are only slightly conical, with no trace of any 
inclusion; some having a thin axial rod in the cone which stains 
readily in iron hematoxylin; some in which this rod is thicker 
and longer, and more deeply staining, and others contain the 
fully formed refractive body. In these four forms or ‘types’ Van 
Beneden thought he saw the complete development of this body. 
His reasoning seemed so logical and his figures so in keeping with 
all observations that most of the students in this field have 
accepted his conclusions. 
O. Hertwig (’90) and Brauer (’93) did not follow the devel- 
opment of the sperm beyond the formation of the spermatid. 
These authors gave special attention to the nuclear phenomena, 
although they describe and figure cytoplasmic inclusions as they 
appear throughout the growth period and maturation divisions. 
Tretjakoff (’05) followed Van Beneden in a study of the com- 
plete spermatogenesis, and concluded with him that the sper- 
matid enters the uterus, there to become the spermatozoon. He 
points out that in many animals the uterine epithelial cells act 
as nurse cells for the developing spermatozoa, and he interprets 
the crowding of the spaces between the epithelial cells of the 
uterus wall with sperm cells of the four types of Van Beneden as 
an effort to get at this necessary food supply. 
‘But Marcus showed that, in A. canis, throughout the later 
‘growth period, maturation divisions and also in the spermatid, 
the cytoplasm contains numerous bodies, rodlike or spherical in 
form, which in the living cell are refringent, like the refractive 
body, and in fixed and stained material resemble that body in 
all staining reactions. In his study of the developing spermatid 
Marcus finds that these bodies, now uniform in size and spherical 
in outline, gradually fuse together and thus ultimately form the 
refractive body itself. Mayer showed that this body is formed 
in exactly the same way in A. megalocephala. His work is 
confirmed by Romieu,? and I have seen the same phenomenon. 
2 The authors just named explain the long delay in the discovery of the place 
and manner of formation of this body. They find that in only one male out of 
thirty killed is the development of the sperm cells in just the right stage to show 
this formation. This proportion is so small that we are not surprised that the 
