: 



1920] SEIFRIZ— PROTOPLASM 377 



dense, while the streaming plasma is much more dilute. Th 

 change from one state to the other is dependent upon (or at least 

 coincident with) physiological (or physical) activity. 



The changes in consistency so far considered have had to do 

 only with the one phenomenon of streaming. There are several 

 other factors which bring on changes in protoplasmic consistency, 

 however, such as development (growth), reproduction, mitosis, 

 and pathological conditions. These changes may be in one direc- 

 tion only, and relatively permanent, as the change from a liquid & 



state to a highly viscous one in the process of fruiting in Myxomy- 

 cetes; or they may be periodic and reversible. The latter type is 

 exemplified in the changes which accompany streaming. Of the 

 former type the gradual increase in consistency during develop- 



- 



ment of the egg of Fucus is an example. 



Developmental changes in viscosity. — The developmental 

 change in viscosity has been fully described in my former publica- 

 tion (23), The protoplasm of young uninucleate oogonia is of liquid 

 consistency (v.v. 3). I think this value is more accurate than the 

 "very liquid" one given in the former publication referred to. 

 Nearly mature oogonia, in which division into 8 eggs is just com- 

 plete, are of slightly viscous consistency (v.v. 4). As the eggs 

 near matuiity they increase to the rather viscous stage (v.v. 5), 

 and the fully mature, normally discharged egg is decidedly viscous 

 (v.v. 6). It is interesting to note that this progressive increase in 

 consistency is coincident with a decrease in physiological activity. 

 The young oogonium with protoplasm of liquid consistency is in a 

 state of active growth, while the decidedly viscous ripe egg is in 

 a more or less quiescent state awaiting fertilization. 



Reproductive changes in viscosity. — I have already referred 

 to the increase in viscosity of a Myxomycete plasmodium as it 

 prepares to fruit. The liquid density (v.v. 3) of the active vegeta- 

 tive stage becomes, when inactive, extremely viscous (v.v. 8), 

 and, on preparing to fruit, increases to a gel consistency. 



Changes in viscosity during mitosis.— Division following 

 fertilization in marine ova brings on very decided changes in 

 viscosity. Earlier work on the ova of Fucus gave evidence of a 

 marked decrease in consistency of the egg protoplasm within half 



