ANALYSIS OF FORM REGULATION. 1/3 



readily and more completely acclimated than the longer pieces and 

 outlive them. In short the more extensive the regulatory reor- 

 ganization of the piece the younger it is physiologically, and 

 vice versa. These facts bear upon the general problems of age 

 and " rejuvenation." 



X. Conclusion. 



The above brief statement of results includes only the more 

 important features of the experiments, but is, I think, sufficient 

 to demonstrate the value of the method and the possibility of its 

 application to various problems.. I hope to extend the experi- 

 ments with these and other substances and with other species, in 

 order to obtain a broader basis for comparison. I scarcely need 

 call attention to the possibihties of the method for the analysis of 

 morphogenetic phenomena. 



The results attained by anaesthetics can be approached more 

 or less closely and in certain respects by decreasing the supply 

 of oxygen, by low temperature and by starvation. In this 

 respect my experiments are in accord with the hypothesis sug- 

 gested by various authorities, viz., that anaesthetics inhibit to a 

 greater or less extent the fundamental metabolic reactions or 

 certain of them. We shall probably find, however, on further 

 experiment that different anaesthetics act differently in certain 

 respects as regards the morphogenic processes. 



Hull Zoological Laboratory. 

 University of Chicago, 

 December, 1909. 



