489 
and caryoplasma, staining with safranin, minute violet staining gra- 
nular bodies, which seem to form the mitotic spindle. In the sper- 
matid these granular bodies are no longer in the nucleus, but in the 
cytoplasm, and I will refer to their fate, when speaking of the Neben- 
kern. Centrosomes are also present and of them I will also speak 
below. 
(2) Constituent Parts of the Spermatozoon. 
The spermatozoon must be studied alive. It is so extremely 
delicate that the greatest care must be exercised in technique. Satis- 
factory permanent preparations are scarcely to be hoped for. No one 
method should be relied upon. The results which I have obtained 
from living cells stained upon the slide, the changes being watched 
under the microscope, have been confirmed by killed and hardened 
material. For the latter, I have teased the testes, in various con- 
ditions of advancement towards maturity, in a very small quantity of 
sea water: then FLEmmınG’s Chrom-osm-acetic, strong formula; or 
Platinum chloride 0,3°/, for 24 hours, or more: wash in water for 
24 hours; stain either in safranin, gentian violet (decolorize in water 
slightly acidulated), or in DELAFIELD’s Haematoxylin; mount in glyce- 
rine; dissociate cells by tapping coverglass gently. 
The living spermatozoa are best examined teased on the slide 
in a carefully filtered solution made by adding a concentrated aqueous 
solution of dahlia to sea water. It must be freshly prepared ‘to give 
the best results. After a few minutes add upon the slide a small 
drop of methyl green prepared in a similar way. Put on the cover- 
glass and examine immediately. Many spermatozoa are still alive. 
The nucleus is colored a delicate green; the Nebenkern a violet; 
while at the anterior end is a small body also colored violet. This 
body, giving with the various reagents a reaction entirely different 
from that of the nucleus, or any of its constituent parts, but closely 
agreeing in its reactions with the Nebenkern, I have found from fol- 
lowing out its history to be the sperm centrosome. The spermatozoon 
then consists of the following parts: 
nucleus 
centrosome | head proper 
A. Head 
a Nebenkern \ the socalled “middle piece” 
cell membrane 
B. Tail. 
Each of these parts with its history is hest considered separately. 
