164 CARL RICHARD MOORE. 



increase enormously in size. The sperm head becomes broken 

 up into pieces but these are retained at the periphery of a clear 

 vesicle and are not scattered promiscuously about in the cyto- 

 plasm. All sizes of these vesicles are present from a mere loosely 

 arranged condition of the content of the sperm head to vesicles 

 larger than the female pronuncleus. These vacuoles appear 

 everywhere within the cytoplasm and are usually lined by heavy 

 black granules. 



The point to be emphasized is this. Sperm enter these eggs 

 in large numbers; they are not only found lying just within 

 the surface of the protoplasm but are found all through the egg 

 cytoplasm, peripheral and central, yet these sperm never give 

 the slightest indication of changes characteristic of fertilization. 

 No asters have ever been found, no spindles have ever been ob- 

 served, though hundreds of cases have been closely studied. 

 Neither does the egg pronucleus give any indication of response 

 following entrance of the sperm. These sperm nuclei become 

 enlarged to a very great extent, the sperm become vacuolated 

 and disintegrate but the eggs are not fertilized ; they never cleave 

 normally and no larvae appear in the cultures. 



No great claims can be made that these eggs have suffered 

 the initial changes in fertilization for in no case has the writer 

 recorded or seen a typical membrane produced as a result of 

 exposure to higher than normal temperatures. The eggs how- 

 ever remain intact and exhibit no power of fertilization even 

 though they become literally loaded with sperm. Immediately 

 we must face the question, why do they not fertilize? What is 

 the character of the change in the makeup of the egg?' 



Loeb has gone so far as to say that development is impossible 

 on account of death. "I found that by merely warming sea 

 urchin eggs to 34 C. or 35 C. the formation of a typical fer- 

 tilization membrane cap often, but not always, be induced. If 

 the eggs are then cooled quickly, no cytolysis follows. Such 

 eggs are no longer capable of development, since a temperature 

 of 34 C. kills them." 1 Loeb's only criterion of death is failure 

 to develop after the addition of sperm. By such an argument 

 one could prove that eggs following complete membrane pro- 



1 "Artificial Parthenogenesis and Fertilization," page 185. 



