34 Cutler, Parthenogenesis in Animals 



periments he showed that artificial parthenogenesis could be 

 induced in the egg of Echinoids by the following methods :■ — 



i. Eggs were treated for ii/ 2 — 3 minutes with a solution of 

 50 cc. sea-water -j- 3 cc. butryic acid. The eggs were then 

 transferred to normal sea- water for ten minutes. Fol- 

 lowing this they were placed for one hour in a hyper- 

 tonic solution of sodium chloride, and then transferred 

 to normal sea-water for development to proceed. 



2. Eggs were first treated with a saponin solution and then 



placed in hypertonic sea-water, followed by normal sea- 

 water. 



3. Eggs were treated -with strong hypertonic solutions and 



then with normal sea-water. 



By these three methods a fall of electrical resistance was 

 produced. "McClendon had stated that this fall was dependent on 

 the presence of an excess of alkali in the interior of the egg. 

 This Gray found not to be the case. The resistance of the egg 

 was also found to be markedly changed by trivalent positive or 

 negative ions, hydrogen ions or hydroxyl ions. All these are 

 known to polarise the membranes, and from this the conclusion 

 was drawn that by the polarisation of the surface of the egg 

 variation in electrical resistance was brought about leading to 

 surface changes and altered permeability. 



Theory of Bataillon. 



The above theories have all been developed largely from experi- 

 ments upon Echinoderm eggs or those of other Invertebrates. 

 Bataillon has for the most part confined his attention to the lower 

 orders of the Vertebrates. Koulaguine ( 1 898) treated Amphibian eggs 

 with anti-diphtheric serum and induced the beginning of develop- 

 ment. Later Bataillon confirmed this 'result and explained it as 

 due to dehydration. 



In his early researches the agents employed were very various 

 and in manv cases his technique was much cruder than that, of his 

 contemporary observers. Thus by pricking the unfertilised eggs 

 of the frog he was able to produce segmentation, which pro- 

 ceeded up to the morula stage in the majority of cases, though 

 three of the eggs developed into tadpoles which lived until 

 metamorphosis. 



A temperature of 40 C. followed by freezing also caused 

 morulas to be formed. In 1900 the effect of different hypertonilc 

 solutions were tested, but in no case did development continue 



