208 PROTOPLASM 



it up again (syneresis) rapidly enough to permit contraction and 

 relaxation two hundred times a second. Gortner states that a 

 contracted muscle has a higher water content than has a relaxed 

 muscle. 



Aging may be a matter of drying up — the reverse of imbibi- 

 tion — but whether we get old because we dry up or dry up because 

 we get old is a question. In any case, it appears that the capacity 

 of our protoplasm to hold water decreases with age. Ru^icka 

 attributes aging to a less hydrated condition of the protoplasm, 

 due to the gradual going over of albumin into globulin, which 

 albumin does spontaneously. 



Body form, in certain instances, may be due to dehydration — 

 the reverse of imbibition. Hatschek suggests that the gastrula- 

 tion of an embryo takes place in the same manner and for the 

 same reason as does the invagination of a two-thirds segment of 

 a sphere of gelatin on drying. 



