] 10 BULLETIN : MUSEUM OF COMPAKATIYE ZOOLOGY. 



All of these must, according to 17, 25, and 26, be considered as 

 determined by the unknown (molecular ?) structure and activities of 

 the protoplasm. 



31. It follows from 30 that the early development of Asplanchna, to 

 a stage somewhat beyond gastrulation, may be analyzed into two fac- 

 tors : (1) the influences determining and preserving the form of the 

 egg as a whole, and (2) processes occurring in consequence of the spe- 

 cific (molecular ]) structure and activities of the protoplasm. 



Both of these factors, which perhaps should be considered as different 

 manifestations of one, are from a causal-mechanical standpoint, entirely 

 unknown. '*' Damit werden die causalen Bedingungen der Entwicklung 

 Torzugsweise in das Moleculargeschehen verlegt und entziehen sich 

 vorderhand grossentheils imserer weiteren Erforschung." (Roux, '85% 

 p. 427.) 



