PROTOPLASMIC STRUCTURE 



27 



same condition is brought about in undifferen dated protoplasm by its 

 unceasing movements, through the growth and collapse of vacuoles (de- 

 fined on page 48) by digestive currents through the animal, and in other 

 comparable ways. The importance of water as a food and for other 

 uses in the tissues is readily observed. 



FIG. 6 



A protoplasmic particle. This highly diagrammatic illustration is intended to suggest the com- 

 plexity and the instability of the unitary particle of protoplasm. At the center, perhaps, is 

 protein with cyanogen (CN) as its core. Closely associated are a fat molecule or group and 

 a carbohydrate molecule or group. Nearby are various anabolic materials and katabolic 

 products often as complex as the fats, etc. Some of the groups about are partly disintegrated. 

 Water and oxygen and carbon dioxide and salts are everywhere about and enzymes are not 

 wanting. 



The second important class of the constituents of protoplasm is 

 included under the term proteins. These are the most abundant con- 

 stituents of the nucleus and the cytoplasm. In the former they contain 

 phosphorus, and are called nucleins. The cellular proteids, especially 

 in the nucleus, according to the important theory advanced by Lilienfeld, 

 Altman, and others, are all combinations in various proportions of one 

 phosphorus-containing substance, nucleic acid, with several proteid-like 



