80 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
which is one of the most important of the processes in early 
development — is the problem of differential imbibition of water. 
This conclusion seems to me of importance for morphogenesis, for 
it enables us to state certain elements of the problem in simpler 
terms. Differential growth occurs because at the appropriate time 
the germinating organ gains that chemical condition which invests 
it with the imbibitory property. 
Fig. 6. The continuous line (a) represents the weights in fractions of a kilogram 
attained by guinea pigs from birth until 12 months old. The broken line (b) represents 
the daily percentage increments (%’s at the right) of the same guinea pigs up to 7 
months. After Minot, Journal of Physiology, 1891, vol. 12. 
