3 

 The Protoplas/fiic Systef?i 



ey^S ALREADY STATED, THE PROTOPLASMIC SYSTEM DOES 



not always reveal itself as consisting of one nucleus and 

 surrounding cytoplasmic mass, though this type is very 

 widespread in occurrence. There are living things in which 

 a discrete nucleus can not be discerned and on the other side 

 we know formations which show many nuclei embedded in 

 one continuous cytoplasmic mass. Thus, we may distin- 

 guish three types of the protoplasmic system according to 

 the extent to which the nuclear substance is differentiated. 

 A classification of the types of the protoplasmic system 

 could also be made on the basis of the degree of the differ- 

 entiation of the ectoplasm. But inasmuch as nuclear 

 differentiation has up to now been more thoroughly studied, 

 it is chosen here as the basis for a classification. 



Some bacteria and blue-green algae have been reported as 

 non-nuclear organisms. In them nuclear substance may, 

 however, be deposited as granules so finely subdivided that 

 they escape detection.^ Indeed, in some cases whilst no 

 formed nuclei or nuclear areas could be located, the presence 



^ The presence of nucleic acid in bacteria has been reported. 

 Schaffer, Folkoff and S. Bayne-Jones {1Q22) extracted from ^00 

 grams of dehydrated bacteria grown on a syyithetic medium free from 

 purine and pyrimidine compounds {constituents of nucleic acid) a 

 non-hygroscopic^ protein-free^ powder which they consider a nucleic 

 acid, though it contained no pentose, the sugar of plant nucleic acid. 

 In the opinion of W. Jones and Folkoff {ig22) the substance is a 

 nucleic acid. 



31 



