266 PROTOPLASM 



that an animal cell (echinoderm egg) obeys the laws of osmosis. 

 This would imply that the cell is a sac containing a solution. 



When water is injected into a cell, it often perfuses the proto- 

 plasm quickly. This is no more miscibility than the taking 

 up of more water by a partially filled sponge. When a sponge, a 

 block of gelatin, or protoplasm reaches its maximum capacity 

 to hold water, it takes up no more. This is not true of solutions, 

 except when confined in an osmotic sac (which is the viewpoint 

 of the opponents of protoplasmic organization). 



Whether we turn to newer work on the physiology of the cell 

 or to older work in cytology, we find support for a semirigid 

 framework in protoplasm. Scarth has demonstrated "a sup- 

 porting skeleton" and a matrix in protoplasm, adding further 

 that cytoplasm is characteristically elastic, that the impression 

 of fluidity is illusory, and that the architectural features of a 

 cell give a structural basis for organization. Spek corroborates 

 this observation. 



The older workers in cytology held similar opinions, expressed 

 in the "spongioplasm" (framework) and "hyaloplasm" (inter- 

 vening fluid) of Ley dig and the "ground substance" and "retic- 

 ulum" of Carnoy and others. E. B. Wilson states that the 

 "continuous substance" {i.e., spongioplasm) is the most constant 

 and active element and that which forms the fundamental basis 

 of the protoplasmic system, to which E. G. Conklin agrees in 

 saying that protoplasm is composed of a more fluid and a more 

 viscid portion. He bases his statement on experiments in 

 centrifuging the eggs of Crepidula, where he found that the more 

 fluid portion of protoplasm may be readily moved but the more 

 viscid portion not so readily; also, the more viscid part of the 

 protoplasm holds the nucleus in place in definite relation to the 

 periphery of the cell and brings parts -back to their normal posi- 

 tions when once they have been displaced by centrifuging. 

 Conklin concludes that the polarity and general organization 

 of the egg reside in the more viscid substance and not in the 

 more fluid medium. 



Alsberg, writing nearly twenty-five years ago, said, "A study 

 merely of chemical constitution, however necessary, will carry 

 us but a very little way in understanding even the simplest 

 processes which take place in protoplasm, unless it is combined 



