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reserve stock of germ-plasm, or in the soma during its 

 ontogenetic development. Thus, according to Weismann, the 

 case of Chrysopha/nvA phlaeas, instead of supporting the theory 

 of the inheritance of somatic modification as at first sight it 

 may seem to do, in reality gives additional weight to the 

 theory of the continuity of the germ-plasm, and its independ- 

 ence of somatic change. But it may properly be called an 

 instance of the inheritance of an acquired character, though 

 not in the Lamarckian sense. The transmissible character 

 has been acquired ; not, however, through the medium of the 

 soma, but directly by the germ-plasm itself. The germ-plasm, 

 therefore, is indeed continuous, but not unassailable by 

 external influences. 



This important biological result was, as we have seen, 

 reached by Weismann in consequence of a combined investiga- 

 tion by observation and experiment on a species of butterfly ; 

 and it is particularly worthy of note by entomologists that all 

 the data which he could obtain respecting the local and 

 seasonal variations of the form in question proved to be of high 

 significance in the solution of his problem. Without them he 

 could not have reached his conclusion ; with further informa- 

 tion on these and similar points, he could no doubt have made 

 his explanation still more complete. This is a good illustration 

 of the way in which observation in the field, experiment in the 

 laboratory, and reasoning in the study can combine to establish 

 a result of great scientific importance. 



It will no doubt have occurred to you that Weismann's 

 view as to the nature of the seasonal dimorphism manifested 

 in the Ligurian form of C. y>hlaeas ought to be tested by 

 exposing the immature stages of the spring brood of this form 

 to a high temperature. So far as I am aware the experiment 

 has not been tried ; and until it has, this part of Weismann's 

 conclusion cannot be accepted without reserve. But as to his 

 view of the susceptibility of the germ-plasm, there has now 

 been abundant confirmation ; again, be it noted, by work 

 done on insects. 



Standfuss, as Weismann notes, bred some specimens of 

 Vanessa urticae under conditions of artificially lowered 

 temperature. The perfect insects showed a departure from 



