20 



Jager (1879). 



Continuity of the germ-protoplasm which receives 

 flavor- and odor-substances from the body- 

 cells. 



Brooks (1876, 1883). Modified theory of Pangenesis. 



Continuity of germ-cells. 



Gemmules given off by body-cells only under 

 unfavorable conditions. 



Sperm-cells especially modified to collect gem- 

 mules. 



Gemmules cause variation in the corresponding 

 part of the offspring. 



" The occurrence of a variation is due to the di- 

 rect action of external conditions, but its pre- 

 cise character is not." 



" The structure of the adult is latent in the egg," 

 Evolution. 



Evidence. 



NussBAUM (1880-1887). 



Continuity of germ-cells. 



Nageli (1884). Theory of the Idioplasm. 

 Formation of " Micellae." 

 "Idioplasma" and " Niihrplasma." 

 Net-work of idioplasm. 

 Micellar threads, one for each character. 

 Their union to form idioplasmic cords. 

 Elementary and complex characters. 

 Same elements in all jjarts of the idioplasm. 

 Germ-cells. 



