PROTOPLASMIC STRUCTURE 33 



hydrolysis it is split into dextrose and galactose. The epithelial proto- 

 plasm of the mammary glands makes lactose, probably from the dextrose 

 of the blood. The important amylose or polysaccharide of protoplasm 

 is glycogen, the animal homologue of vegetable starch. Its formula is 

 (C 6 H 10 O 5 )n, in which the n is probably six, making the probable formula 

 of glycogen (C 6 H 10 O 5 ) 6 , while that of vegetable starch is most likely 

 (C 6 H 10 O 5 ) 20 . . This essential and interesting substance was discovered 

 by Claude Bernard in 1857, and was called glycogen by him because he 

 found it to be the immediate source of the tissue-sugar, dextrose. Glyco- 

 gen is made from proteids, albuminoids, and carbohydrates in the food 

 of the animal. It probably is a constituent of every living animal cell, 

 as its homologue, starch, is of every vegetable cell. It may be glycogen, 

 or some body very similar, which joins with the proteid and the 

 " inorganic" salts to constitute the huge, labile, and changeful particle 

 characteristic of life. 



The last class of compounds which enter regularly into protoplasm are 

 the inorganic salts. These are crystalloids, while the others, except water, 

 are generally either fats or colloids known as "hydrosols." Reference to 

 the systematic and summarizing table of proximate principles on page 

 30 will show just which of the inorganic salts are universal in proto- 

 plasm. Of these, the chlorides and phosphates of calcium, sodium, and 

 potassium are doubtless the most important, and perhaps are the only 

 ones universally present in bioplasm, undifferentiated or differentiated. 

 Their source to the animal is obviously the food both of vegetable and 

 animal origin, for all plants and all flesh contain these salts. One of the 

 doubtful and difficult matters to decide in physiology at present concerns 

 the extent of the usefulness of these " inorganic" salts (the name is obvi- 

 ously misleading) in animal protoplasm. Through physical chemistry 

 the new movement in biophysics has developed rapidly of late, and 

 A. P. Mathews, Loeb, Nageli, and Hardy have opened fields involving 

 ions and the theory of electrolytic dissociation which are likely to define 

 wherein lies the great importance of these inorganic salts. Osmosis, 

 hydrolysis, and coagulation are important processes in animal metabo- 

 lism, yet they (and possibly muscular contraction and nervous conduction, 

 etc.) may be wholly dependent on these salts for their accomplishment. 

 It is on little differentiated protoplasm that many of these researches 

 have been made, the sort that makes up the infusoria and other unicells 

 and simpler multicells; and the investigations have shown conclusively 

 that any considerable change in the inorganic salt content of these forms 

 is disastrous to the animal. In the "high" forms of life the same fact is 

 obvious in many ways. The most elaborate means are employed by the 

 most highly developed animals to secure the uniformity of the composition 

 of the tissues from time to time, and especially as regards the crystalloids 

 or electrolytes of the circulating, but all-pervading fluids. Thus, whether 

 ions are important in animal metabolism or not (and few today doubt 

 their importance), salines can be proved to be so in many different 

 respects and in every location within the bodies of living animals. Nothing 

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