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. 1 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. 



