ibys RAYMOND BINFORD 
concentration the eversion continued, but the wall of the part 
already everted seemed to be hardened, so that it made an 
elongated collar through which the further inversion took place. 
The effect of reagents on the everted spermatozoa 
After trying several fixing reagents it was found that for 
imbedding and cutting the crab’s eggs Morgan’s fluid gave de- 
cidedly the best results. This fluid is a saturated solution of 
picric acid in 30 per cent alcohol, to 100 ce. of which 2 ce. of 
H.SO, are added. Spermatozoa in various stages of the process 
of inversion and those in the normal mature condition were 
mounted under the microscope and killed with this fluid in order 
to determine its effect upon them. A considerable amount of 
shrinking was observed, but no decided change in the relation- 
ship of the parts seemed to take place. Figures 86 and 87 were 
drawn from spermatozoa exploded in distilled water, fixed in 
Morgan’s fluid, stained in thionin and eosin, dehydrated in alco- 
hols, cleared in xylol and mounted in balsam. ‘The general rela- 
tions of the parts is the same as in figures 81 and 82. The space 
between the everted tubule and the inverted capsule seems to 
have shrunk relatively more than the inverted capsule. Having 
now observed the behavior of spermatozoa under experimental 
conditions we may proceed to our observations concerning the 
extrance of the spermatozoon and the process of fertilization. 
7. THE ENTRANCE OF THE SPERMATOZOON 
Eggs were taken from the lumen of the ovary just after the 
crab began to spawn, and were fixed in Morgan’s fluid, imbedded 
in paraffin and sectioned. A microscopic examination of these 
eggs showed the spermatozoon in the act of entering the egg. 
The best stain for the study of these sections is thionin, for it 
stains the chromosomes in the mitotic figure of the nucleus of 
the egg and the nuclear cup of the spermatozoon a deep blue. 
It stains the everted portion of the spermatozoon faintly and the 
food material, cytoplasm and egg-shell are unstained or only 
