66 HARRIETT M. ALLYN. 



in Chcetopterus are associated with a very brief period of activity 

 and are not sufficient of themselves to induce development. 



4. Development to swimming larvae may take place whether 

 one or both polar bodies are extruded, or if both are retained 

 within the egg. 



5. Maturation and differentiation may be controlled by dif- 

 ferent conditions, indicating more or less distinct sets of reactions 

 for the two processes. 



6. Maturation may go on in reduced oxygen supply, or in 

 suppression of oxidation by potassium cyanide. Hydrolyses are 

 probably concerned in maturation, therefore, or other processes 

 which can take place with very low rate of oxidation. 



7. High rate of oxidation interferes with maturation. 



8. Differentiation requires an increased supply of oxygen over 

 that contained in the resting, unfertilized egg. 



9. Differentiation involves oxidation. Suppression of oxida- 

 tion by potassium cyanide, even for a brief time, during the 

 differentiation period, hinders differentiation. 



10. Excess of oxygen in the sea- water after the completion of 

 maturation may induce cleavage. 



1 1 . The effect of heat in inducing cleavage is probably due in 

 part to the intake of more oxygen by the egg, owing to increased 

 permeability of the membrane, also to the increase in rate of 

 oxidations. 



12. Cleavage requires that the normal nucleo-plasmic relations 

 for development shall be set up, such that reactions may take 

 place in correlation. This is attained by the action of heat which 

 affects all regions and membranes of the egg at approximately the 

 same time. 



13. The use of an artificial parthenogenetic agent before 

 fertilization is prejudicial to normal development. 



14. The use of two physico-chemical agents to induce artificial 

 parthenogenesis suppresses the development called out by either, 

 unless the action of one is supplementary to that of the other. 



I wish to acknowledge my indebtedness to Professor F. R. 

 Lillie, of the University of Chicago, for the use of his Chcetopterus 

 material, and for the many kind and very helpful suggestions 

 given during the progress of my work. 



