No. 4.— Further Studies on the Spermatogenesis of Caloptenus 
femur-rubrum. By E. V. Wicox. 
A continuation of the study of the spermatogenesis of Caloptenus 
femur-rubum has served to confirm many of the results gained last year 
(Wilcox, 95), and has made it possible to give a fuller account, particu- 
larly of the metamorphosis of the spermatids. 
The material for this year’s work was collected during the months of 
August and September. The testes were killed by nearly all the stand- 
ard methods. Hermann’s fluid and Vom Rath’s modification of it gave 
the best results. With my material it is more easy to stain after Vom 
Rath’s than after Hermann’s fluid. The spindle fibres and ‘ Neben- 
kern” are rendered very distinct by Hermann’s fluid, no staining being 
required if the testes are left in this fluid for several hours. I found 
it unnecessary to use pyroligneous acid to differentiate the various cell 
structures. 
For staining I used Heidenhain’s iron-heematoxylin with good results. 
It stains excellently both sections, and zm toto. Biondi’s mixture was used 
with only moderate success. With low powers there appears to be a very 
marked differentiation in colors, but the staining is so faint that with 
high powers it is very difficult and trying for the eye to make out fine 
details. I tried with good success the modification of Flemming’s 
orange method as given by Reinke (94, pp. 261-263). The only diffi- 
culty I met with was in preventing the gentian violet from being washed 
out. This last method brings out very clearly a body in the vacuole of 
the nucleus of the spermatid (Plate 3, Figs. 94-98). 
I will now give a brief account of my own work on the various stages 
in the development of the male sexual elements, and then a criticism of 
some recent papers bearing on the subject. 
The stage in the division of the spermatogonia which is most common 
is the dyaster (Plate 1, Figs. 1, 2). All the spermatogonia in a singie 
compartment are often in almost exactly the same condition (Fig. 2). 
1 Contributions from the Zodlogical Laboratory of the Museum of Comparative 
Zoology at Harvard College, under the direction of E. L. Mark, No. LVIII. 
VOL. XxXIx. — NO. 4. 1 
