322 WILLIAM SEIFRIZ. 



tence of a great number of reactions, constantly going on without 

 one interfering with the other. This demands the division of 

 the contents into innumerable chambers or centers of activity. 

 Thus does the protoplasm possess, in a sense, structure. The 

 presence of these miniature laboratories is well illustrated by the 

 behavior of disintegrating ova in which the dissemination of the 

 inclusions is at times in certain regions extremely rapid, and in 

 others non-existent (Figs. I and 2). The difference in the phys- 

 iological state of the protoplasm at any one moment is respon- 

 sible for the variety of behavior of eggs from the same oogonium 

 and of parts of the same ovum. This difference is to be expected 

 if protoplasmic activity takes place in pulsations, which are 

 neither synchronous among the eight eggs of one oogonium nor 

 rythmic in any single ovum. The cell is, then, a laboratory in 

 which many different chemical reactions are constantly going 

 on, kept free from one another by boundaries of some kind. 

 (Hofmeister, 1901.) 



Structure in protoplasm is secondary to activity. Upon the 

 chemical nature of the substances does the life of the cell depend 

 rather than on their arrangement. What physical structures 

 may exist are of a transitory nature. This interpretation does 

 not preclude the all-important organization upon which the con- 

 tinuance of these activities depends. 



SUMMARY. 



1. Protoplasm is an emulsion colloid normally in the sol state. 



2. The density of protoplasm varies from the very liquid state 

 of young Fucus oogonia and embryos and of streaming proto- 

 plasm in myxomycetes and pollen tubes, to the quite viscous 

 condition found in mature and resting eggs of marine organisms. 



3. There is a rapid increase in viscosity of the Fucus egg 

 during the last stages of its ripening, which is, on fertilization, 

 followed by a return to the liquid consistency characteristic of 

 active, growing proptolasm. 



4. The plasma membrane is a definite morphological struc- 

 ture, constantly and repeatedly capable of repair through the 

 conversion of the fluid protoplasm into a hyaline layer of greater 

 molar concentration. This film of gel is exceedingly elastic, 

 pliable and glutinous. 



