FACTORS CONCERNED IN THE PRODUCTION OF 



MITOSIS IN ORGANISMS DISPLAYING 



CELL CONSTANCY. 1 



H. J. VAN CLEAVE. 



The condition of absolute identity in cellular structure found 

 in individuals of many species of Metazoa has led the writer to 

 undertake an analysis of the factors governing mitosis in these 

 forms. Loeb ('12: 4) has called attention to the fact that the 

 first attempt to reduce the phenomena characteristic of life to 

 purely physico-chemical terms is found in the works of Lavoisier 

 and Laplace ('80) which indicated that the heat produced in the 

 body of a warm-blooded animal equalled that given off by a 

 burning candle when the amounts of carbon dioxide produced 

 in the two instances were equal. These results have been so 

 much amplified by later workers that today no one doubts that 

 the general processes having to do with the phenomena of meta- 

 bolism are identical with the so-called purely physical and 

 chemical reactions occurring outside the living body. In fact 

 while metabolism, movement, and irritability are generally 

 granted as probably due to the workings of the same principles 

 that govern the inanimate realm the fourth of the vital properties, 

 that of reproduction, is in great part still unexplained. No 

 problem has offered more secure harbor for a final possibility 

 of the presence of some supernatural force than has this one 

 dealing with the processes of reproduction. The statement of 

 Davenport ('08: i); "The vital processes are chemical processes, 

 taking place in a highly complex, very unstable, constantly 

 changing substance, whose activities we call life," embodies the 

 modern conception of the nature of life phenomena in general, but 

 no attempt has been made to show the actual possibility of 

 explaining all life processes on this basis. 



An analysis of the possible factors determining or directing 



1 Contributions from the Zoological Laboratory of the University of Illinois, 

 No. 43. 



