304 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 
culatus, which he placed in sea-water containing an extract of 
the eggs of the same species and found that under these condi- 
tions the spermatozoa swelled so as to lose completely their 
normal appearance. The tail remained unchanged, but the 
cytoplasmic covering of the head, the middle piece, and the 
chromatic portion of the head all seemed to swell; and in some 
cases an indistinct vesicular structure was seen which stained 
a little stronger than its surroundings, and seemed to be a 
nucleus. He concludes that incomplete as his results may be, 
they give a right to conclude, “that the male just as the female 
cell is capable of evolution under the influence of external 
agencies.” 
Loeb and Bancroft undertook experiments to see whether 
the spermatozoon could be caused to develop in vitro on suitable 
nutritive media.' Their experiments were carried on on the 
sperm of the fowl. The sperm was removed aseptically. Only 
the sperm contained in the lower portion of the vas deferens 
was used. It was kept in a sterilized moist chamber at about 
39° C., but was always used soon after its removal from the 
animal, not later than three hours after it was taken out. The 
media used for the culture of the spermatozoon were: egg 
yolk, egg albumen, chicken blood serum, and m/6 and m/10 
Ringer solutions. Slides, cover glasses, and instruments were 
sterilized in a flame and small hanging drops of the various media 
were inoculated with the spermatozoa. The cover glasses were 
inverted over hollow slides and sealed with a vaseline and 
paraffin mixture. In a few cases the eggs were broken into 
glass vessels and small quantities of sperm injected into the 
yolk with a capillary pipette. After stated intervals yolk and 
sperm were taken out for examination with a capillary pipette. 
When the spermatozoa of the fowl are observed in a hanging 
drop of white of egg, kept at about 40° C., the first change is 
seen after fifty or sixty minutes. It consists in the collection 
Loeb and Bancroft, Jour. Exper. Zool., XII, 381, 1912. 
