( xcix ) 
the normal which was no doubt due to the refrigeration,—in 
this case an increase of dark pigment. Eggs were laid by 
some of these abnormal specimens, the resulting larvae were 
reared under normal conditions, and the butterflies on 
emergence again showed a divergence from the normal form 
which, though slight, was in the same direction as that of 
their parents. Similar results with the same species were 
afterwards obtained by Weismann himself. A still more 
marked confirmation was supplied by Fischer. Pupae of 
Chelonia caja were subjected to an artificially lowered 
temperature, and some of the resulting moths showed an 
extreme degree of melanism. Two of these artificially-produced 
aberrations were paired, and their offspring were reared 
under normal conditions. Among the latter were specimens 
which exhibited in greater or less degree a tendency towards 
the artificially-induced melanism of their parents. Here we 
have an excellent case of the apparent transmission of an 
acquired character. In the light, however, of Weismann’s 
acute reasoning on the subject of G. phlaeas, there is every 
justification for believing that the same interpretation is valid 
in the present case. The modification is not inherited from the 
soma of the parent, but is consequent upon the direct action of 
the external influence upon that parent’s germ-plasm. 
But all this pioneer work, impoi’tant and excellent as it is, 
must yield the palm for completeness and cogency to the 
laborious researches conducted by William Lawrence Tower, 
whose treatise entitled “ An Investigation of Evolution in 
Chrysomelid Beetles of the Genus Leptinotarsa ” is a perfect 
storehou-se of valuable biological material, all derived from 
the minute study of a single genus of Coleoptera. This 
admirable publication, which appeared in 1906 under the 
auspices of the Carnegie Institution of Washington, has 
perhaps in this country hardly met with the attention which 
it deserves ; though now that Professor Bourne, in his recent 
Presidential Address to the Zoological Section of the British 
Association, has drawn public attention to the work, it may 
be expected that greater appreciation will be shown of the 
extremely interesting results which it contains. 
Among the numerous and carefully-planned experiments 
G 2 
