348 ROXIE A. WEBER. 



individuals emerge from one capsule when the number of eggs 

 found in one capsule varies ordinarily from three to eight. The 

 elongation of those eggs sufficiently far advanced in develop- 

 ment to show this phenomenon is still further indication of this 

 same thing. 



Kleinenberg attributes the cause of this double embryo forma- 

 tion to the entrance of two sperm into a single egg setting up 

 two points of activity. In the light of more modern discoveries 

 this explanation no longer holds good. Vedjovsky suggests the 

 possibility of temperature and moisture changes, and exposure 

 to air bearing their influence on the egg and causing its abnormal 

 development. Until further studies are made along this line 

 it will be impossible to state any definite causes of monster 



formation. 



BIBLIOGRAPHY. 

 Kleinenberg, N. 



'78 Sullo Sviluppo del Lumbricus trapezoides. 

 Vejdovsky, Fr. 



'88-'92 Ueber Zwillingsbildungen der Lumbricidcn. Entwicklungsgeschicht- 

 liche Untersuchung. 



