AN INTRODUCTION TO THE STUDY OF GROWTH. 



33 



That the power to grow is closely connected with the 

 length of life in different animals is beyond question, 

 but a proper formulation of this connection is difficult. 

 Certainly there is as yet no adequate explanation of the 

 fact that some animals live longer than others ; we find 

 that, in general, the larger animals are those having the 

 longer life, and thus long life is to be associated with 

 size ; but, on examining this relation, it appears that 

 size depends upon two factors the rate of growth, and 

 the length of time that growth continues, and animals 

 that attain a large size grow both rapidly and for a 

 long time. Minot has pointed out that if the guinea- 

 pig, 1 rabbit, and man are compared as to their increase 

 in weight the following interesting facts appear : 



TABLE i. SHOWING THE AVERAGE DAILY INCREASE IN 

 WEIGHT DURING THE GROWING PERIOD OF THE GUINEA- 

 PIG, RABBIT, AND MAN. (Afinot.) 



This table shows that the rate of increase in the 

 rabbit and in man is about the same ; but owing to the 

 fact that in man growth continues for about twenty-five 

 years, whereas in the rabbit it stops at the end of one 



, Journal of Physiology, 



3 



