296 C. M. CHILD. 



to doubt that it can under certain conditions undergo fission or 

 fragmentation and still retain the capacity t<> become a "whole" 

 again;' \\V know that the capacity for regulation is a very gen- 

 eral characteristic of living things: are we justified in asserting 

 without the strongest experimental evidence that the nucleus 

 is wholly without this capacity? 



If it were not for the fact that it makes no essential difference 

 for the phenomena of life, including those of heredity, whether 

 the chromosomes are continuous individuals or not this hypothesis 

 would doubtless have been abandoned long ago. But since it is 

 in a sense outside the field of scientific investigation, at least 

 so long as present methods of cell study are in vogue, the chro- 

 mosome theory has developed into a wonderful inverted pyramid 

 of hypotheses in the construction of which the chromosome 

 appears as a veritable dens c.\ muchina. 



The great need of cytology is a substitution of the experimental 

 for the descriptive method: more experimentation and control 

 and less inference from observation, a dynamic rather than a 

 static point of view, rigorous proof rather than loose speculation; 

 with such changes we may hope to gain some knowledge of the 

 cell. The disadvantages of the present method are sufficiently 

 manifest in the present paper. 



II' I.L ZOOLOGICAL LABORATORY, 

 rxivKRsiTV OF CHICAGO, 

 July, ion. 



BIBLIOGRAPHY. 

 Boveri, Th. 



'07 Zellen-Studien, H. 6. 

 Child, C. M. 



'073 Studies on the Relation between Amitosis and Mitosis. I. Development 



of the Ovaries and Oogenesis in Moniezia. Biol. Bull., Vol. XII. 

 'o7b Studies, etc. III. Maturation, Fertilization and Cleavage in Moniezia. 



Biol. Bull., V..1. XIII. 

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Bd. XXX. 



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 Godlewski, E., Jr. 

 '09 Da Vererbung i>mM<-m im Lichte der Entwicklungsmechanik betrachtet. 



Voiti. 11. Ant-. 11. Entwickelungsmechanik, H. IX. 

 Richards, A. 



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