382 JACQUES LOEB AND F. W. BANCROFT 
egg is at the same time an attempt to test the validity of the 
reasons which seem to speak against this possibility. 
There is only one paper dealing with this problem, by J. de 
Meyer.! He raised the question whether it is necessary that the 
spermatozoén should come in contact with the cytoplasm of 
the egg in order to undergo the first phases of its normal evolu- 
tion. He used the sperm of Echinus microtuberculatus, which he 
placed in sea-water containing an extract of the eggs of the same 
species and found that under these conditions 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 struc- 
ture 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” (p. 94). 
Il. MATERIAL AND METHODS 
Our own 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 spermatozo6n were: egg yolk, egg albumen, chicken 
blood serum and § and yo 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 paraffine 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. 
1 J. de Meyer, Arch. de Biologie, vol. 26, p. 65, 1911. 
