Manchester Memoirs , Vol. Ixii, (191 7), No. 2 35 



past the morula condition. Bataillon attributed these results to 

 dehydration, which removed waste products, chiefly C0 2 , which 

 had accumulated in the resting egg. These waste products 

 were supposed to inhibit development, which could only be 

 initiated by their removal. 



This early view was, however, soon modified to give place to 

 a more complicated one in which there was assumed to be factors 

 resident in the blood which act as caralysers. Further, the 'jactive 

 agent was thought to be the nuclear matter of the leucocyttes. 



In order to illustrate the very varied methods that have been 

 employed from time to< timje 'for the production of artificial par- 

 thenogenesis the following list is given, which has been modified 

 from one tabulated by McClendon : — 



1. Hypotonic solutions (distilled water). 



2. Nearly istonic solutions made by adding to sea-water or to 



distilled water the following substances : acids, alkalies, 

 neutral salts. 



3. Hypertonic solutions made by adding acids, alkalies, 



neutral salts. 



4. Non-electrolytes : mechanical shocks, thermal changes, fat 



solvents, alkaloids, blood sera, bile salts, etc. 



5. Electrical shocks by induction coils. 



Conclusion. 



* These various agents are not effective on all species of eggs, 

 in fact, some of the methods 'are only of use for 1 one particular 

 species. It thus appears that there are wide differences between 

 the various kinds of eggs, and that artificial parthenogensis is 

 not induced in the same ma(nri|er fojr all. It /is one of the. 

 problems of the future to ascertja|in if ther'e is Slot a common 

 factor or factors to all the methods which are capable by them- 

 selves of causing unfertilised eggs to develop. Until this is done 

 it is practically impossible to decide what action the sperm has 

 on the egg at fertilisation, causing ;i,t to (undergo the com- 

 plicated series of changes which culminate in the adult animal. 



From the standpoint of the cause of sex production it is of 

 great importance to ascertain what is the sex of the animals pro- 

 duced from artificial parthenogenetic eggs. These eggs have 



* A summary of artificial parthenogenesis by M. Herland has recently appeared 

 in a paper entitled " Le Mecanisme de la Parthenogenese experimentale chez les 

 Amphibiens et les Echinodermes. Bulletin Scientifique de la France, et de la 

 Belgique. 7th Series Ti, 1917. 



