356 THE ZOOLOGIST. 



three adults, all decemlineata. These constituted lot B. The 

 decemlineata of lot A and lot B were reared side by side under 

 normal and exactly similar conditions. The results were striking. 

 From lot B normal progeny were reared up to the tenth generation, 

 and, as usual in the genus, two generations were produced in each 

 year. The decemlineata of lot A segregated into two lots in the 

 second generation. A 1 were normal in all respects, but A 2 , while 

 retaining the normal appearance of decemlineata, went through five 

 generations in a year, and this for three successive years, thus 

 exhibiting a remarkable physiological modification, and one without 

 parallel in nature, for no species of the genus Leptinotarsa are known 

 which produce more than two generations in the year. This experi- 

 ment is a sufficient refutation of Weismann's argument that the in- 

 heritance of induced modifications in Vanessa urticce is only apparent, 

 the phenomena observed being due to the inheritance of two kinds of 

 determinants — one from dark-coloured forms which are phyletically 

 the oldest, and the other from more gaily coloured forms derived 

 from the darker forms. There is no evidence whatever that there 

 was ever a species or variety of potato-beetle that produced more 

 than two, or at the most, and then as an exception, three broods in 

 a year. 



The modified albinic forms in this last experiment of Tower's 

 were weakly ; they were bred through two or three generations and 

 came true to type, but then died out. No hybridization experiments 

 were made with them, but in other similar experiments, which I have 

 not time to mention in detail, modified forms produced by the action 

 of changed conditions gave typical Mendelian characters when crossed 

 with unmodified decemlineata, thus proving that the induced charac- 

 ters were constant and heritable according to the regular laws. 



I have thought it worth while to relate these experiments at some 

 length, because they seem to me to be very important, and because 

 they do not appear to have attracted the attention in this country 

 that they deserve. 



They are confirmed to a very large extent by the experiments of 

 Professor Klebs on plants, the results of which were published this 

 summer in the Croonian Lecture on " Alterations of the Development 

 and Forms of Plants as a Result of Environment." As I have only a 

 short abstract of the Croonian Lecture to refer to, I cannot say much 

 on this subject for fear of misrepresenting the author ; but, as far as 

 I can judge, his results are quite consistent with those of Tower. 

 Sempervivum funckii and S. acuminatum were subjected to altered 

 conditions of light and nutrition, with the result that striking varia- 

 tions, such as the transformation of sepals into petals, of petals into 

 stamens, of stamens into petals and into carpels, were produced. 

 Experiments were made on Sempervivum acuminatum, with the view 

 of answering the question whether such alterations of flowers can be 

 transmitted. The answer was in the affirmative. The seeds of 

 flowers artificially altered and self-fertilized gave rise to twenty-one 

 seedlings, among which four showed surprising deviations of floral 

 structure. In two of these seedlings all the flowers were greatly 

 altered, and presented some of the modifications of the mother plant, 



