.344 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1921. 



body, they modify in a parallel sense the representative colloids of 

 the jrerminal cells, so that there would be a cumulative effect of the 

 same general factor acting on successive generations. It is just 

 this which has been supposed for a long time by Weismann himself 

 and which has been designated by the name "parallel induction" 

 (term of Detto). Weismann 10 has illustrated the fact by the 

 celebrated example of Chrysophanus phloeas. This butterfly of very 

 wide geographical distribution varies according to the seasons and 

 to localities: In northern regions, the upper wings are golden red 

 with a black border and black dots on the disk, the posterior wings 

 blackish with a reddish submarginal band. In southern Europe 

 there are found in the summer generation larger specimens whose 

 two pairs of wings are almost entirely black (form eleus), with 

 all intermediates between this form and the type. If caterpillars 

 coming from eggs of phloeas from Naples are raised in Germany 

 and the pupae submitted to a low temperature (10° C.) , there develop 

 butterflies a little less black than those of Naples, but much blacker 

 than the German ones; on the contrary, pupae of German origin 

 submitted to a high temperature (38° C.) produce butterflies which 

 are a little less fire-red and a little blacker than the ordinary German 

 butterflies. 



The hereditary character of the southern varieties, an abundance 

 of dark pigment, is thus seen to be directed in the same way as the 

 action of the higher temperature. We can suppose that when the 

 species, at first northern, reached the south, the rise in temperature 

 affected, with a like result, the formative elements of wing color, 

 and the colloids representative of the pigment in the germinal cells. 

 Hence the present condition. 



We can perhaps accept the heredity of immunity, an acquired 

 character appearing after a germ disease; not total immunity, for 

 we know well that this is not transmissible, but a partial immunity 

 which is sufficient, without need of recourse to a selection of the most 

 resistant, to explain why the inhabitants of a country where a dis- 

 ease commonly occurs are generally more apt to resist it than those 

 of a country which is free from it, and that diseases which are 

 brought into new countries cause there terrible ravages. Guyer re- 

 ports that rabbits innoculated successively with typhoid vaccine, 

 then with living typhoid germs, can transmit to their young and 

 even to the following generation the property of agglutinating the 

 typhoid bacilli in the dilute serum (this is, however, in contradic- 

 tion Avith previous researches on the transmission of immunity and 

 demands confirmation ; do not the mothers remain bearers of bacilli 

 of weakened virulence which, expelled periodically, would induce a 



10 Weismann, Vortrage fiber Descendenztheorie. Jena, 1902, p. 306. 



