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a sexually ripe female, suspend them in a little ocean water, 

 then add some spermatozoon taken from a male, and ob- 

 serve the development under the microscope. The changes 

 proceed with the regularity of clockwork. The ovum at 

 once forms the fertilization membrane. After a few min- 

 utes the two-cell division occurs. After a few more minutes 

 the four-cell stage is reached, and cell division proceeds. 

 Finally the "blastula" and then the "gastrula" are formed, 

 as pictured in Figure 79. After this, the animal begins to 

 form a "larva," an initial form through which it passes in 

 its development. 



Biologists have long puzzled over how this initiation of 

 the development through the sperm might be explained. 

 It seemed that a definite answer had been found when 

 Jacques Loeb announced in 1904 that he had succeeded in 

 obtaining normal larvae from the unfertilized eggs of the 

 sea-urchin by a certain treatment with acids and, subse- 

 quently, with strong salt solutions. Since Loeb disposed 

 of one of the two parties to normal fertilization it might 

 have seemed, to a superficial observer, that a 50% synthesis 

 of the process of initiating new life was accomplished. 

 This, of course, is by no means a reasonable interpretation 

 of Loeb's experiments; the egg is far more essential to the 

 development of the organism than is the sperm. 



In many species the young develop from the ovum with- 

 out fertilization by the male. Even Aristotle was aware of 

 this, for he states that "bees produce drones without cop- 

 ulation." The same is true for ants, wasps, and other 

 insects. In many cases, therefore, eggs develop without 

 the spermatozoon. In other cases they cannot, but perhaps 

 there is merely a slight handicap of some sort, removable 

 by artificial means. Starting from some such assumption, 

 experiments on artificial fertilization were undertaken by 

 various workers a long time before Loeb entered the field, 

 notably by T. H. Morgan, who treated eggs of sea-urchins 

 and of worms with certain poisonous salts and observed 



