No. 441] NOTES AND LITERATURE. 629 



avowedly unmetaphysical. The felt-need to say in the preface that 

 a scientific book is unmetaphysieal is good evidence of the increasing 

 interest in philosophic problems among biologists. Furthermore, the 

 author who begins by assuring us that he is not going to be meta- 

 physical usually plunges at once into a discussion of metaphysical 

 problems with a naivete which delights the technical philosopher. 

 The ever increasing interest in the morphology of concepts is evi- 

 denced by Driesch in his attention to the meanings of the funda- 

 mental concepts with which he has to deal. However unsatisfactory 



has succeeded in pointing out certain problems which are worthy of 



Robert Yerkes. 



The Biogen Hypothesis. »— Chiefly for the purpose of establishing 

 a clear working hypothesis as to the inner changes of the living cell 

 Verworn has attempted to make more precise the biogen hypothesis 

 based on the investigations of Hermann. ['linger. Khiiich, Allen and 

 others, and to show the wide application of this to the active proc- 

 esses of cells. Biogen molecules, according to Verworn, occur in the 

 cytoplasm, not in the nucleus of the cell. Unlike albumen molecules, 

 they are ordinarily very labile. The nucleus, though containing none 

 of them, gives out material essential to their changes. The cyto- 

 plasm contains in addition to the biogen molecules reserve food mate- 

 rials and oxygen, the Litter in weak combination. In hunger the 

 reserve food of the cell is first used and then certain biogen mole- 

 cules are sacrificed to others. To make good such loss food is appro- 

 priated and is made available to the biogen molecules through the 

 action of the enzymes. The stimulation of protoplasm consists in 

 changing its biogen molecules from a state of high lability to one of 

 low lability, a change brought on by oxidation. The recovery to the 

 state of high lability is an assimilative process that requires time, and 

 is represented by the refractive period in many operations during 

 which stimulation is impossible. Thus the stimulability of a mass of 

 protoplasm is a measure of the completions of the assimilative proc- 

 esses which repair the effects of stimulation so far as the biogen mole- 

 cules are concerned. The hypothesis thus affords a more or less 

 complete history for protoplasmic metabolism. 



