THE PHYSIOLOGY OF REGENERATION 



325 



maximum rate may be due either to the greater impediment 

 resulting from the increase in the size of the growing mass, or 

 to the fading out of the original impetus, which had caused 

 the immense output of growth energy near the start, or perhaps 

 to both factors combined. The principal interest in this connec- 

 tion is that in both normal and regenerative growth the maximum 

 intensity of the process is not attained at the very beginning and 

 is retained for only a comparatively short time. 



P&icemAa/ae- Jruyie/mxyrtyta. )7la£e^. 



25811 n 23 25 3ije 45 60 75 90 lOS 120 135 ISO 165 18 



'.iOcUzyu 



Fig. 3 Curve showing the daily percentage increments in weight of male guinea 

 pigs. Copied from Minot ('07, p. 197, fig. 21). Popular Science Monthly, Septem- 

 ber, 1907. 



THE ROLE OF WATER IN GROWTH 



Long before zoologists had come to realize that 'there was a 

 blank in their knowledge of the physiology of the organism so far 

 as phenomena of growth are concerned, botanists had already 

 thoroughly investigated the problem of plant-growth. It was J. 

 Loeb who, following the example of botanists of Sachs's school, 

 first attempted to analyze the relation of osmotic pressure to 

 animal growth, and thus brought this question to the front. 

 Although later investigations of the influence of osmotic pressure 

 upon regeneration are somewhat at variance with Loeb's conclu- 

 sions relative to hydroids, yet it should be remembered that his 



