July 10, 1896.] 



SCIENCE. 



53 



great deal of new matter relative to the hybridi- 

 zation and seasonal dimorphism of Lepidoptera, 

 the result of some twenty-five years of work. 

 It is therefore a most important contribution to 

 biology, and is another in the series of notable 

 works called out by the epoch-making essays 

 of Weismann contained in his ' Studies in the 

 Theory of Descent,' published over fifteen years 

 ago, when the author was an orthodox La- 

 marck i an. 



The practical topics discussed relate to the 

 mode of collecting, the breeding of larvae, in- 

 cluding pairing of the sexes of the same and of 

 different species. This portion is succeeded by 

 lengthy accounts of certain special cases of 

 hybridization and of hybrids between different 

 European species of Saturnia, with details re- 

 garding the biological, anatomical and physio- 

 logical peculiarities of the hybrids, including a 

 very neat and obviously correct phylogeny of 

 the genus as concerns the European species. 

 This part is followed by generalities on hybridi- 

 zation and hybrids, and on pairing both in con- 

 finement and in nature. 



The egg-state, larva and pupa, their cai'e, arti- 

 ficial hibernation, diseases, etc. , are fully treated 

 from the point of view of one who has reared 

 thousands of specimens in the most successful, 

 <5areful and scientific manner. 



Next to the subject of hybridization that of 

 seasonal dimorphism as discussed by Stand- 

 fuss is of special value, since he brings forward 

 many new facts. It is treated under the follow- 

 ing heads : Albinism, melanism, change of 

 color, exchange of colors, local races, local 

 forms, local varieties, seasonal dimorphism, 

 based on experiments on butterflies (species of 

 Papilio, Rhodocera, Vanessa, Argynnis, and on 

 a moth, Dasychira ahietis. 



The paper succeeding, devoted to thoughts 

 relative to the question of species-formation, 

 <;ontains the author's general view^s, and the 

 book ends with the directions for collecting 

 the imagines. 



It would have been better, we think, if Dr. 

 Standfuss had divided the work into two 

 parts, separating the practical directions from 

 the scientific part, but the result will be that 

 the amateur and collector will be perhaps, in 

 some cases at least, insensibly led to become a 



scientific observer, and thus great good will re- 

 sult in placing the study of insects on a higher 

 plane. 



The results of the experiments in keeping the 

 pupa of Papilio Machaon at a temperature of 

 98-99° F. produced not only changes in mark- 

 ings and hue, but also in form, such as the length- 

 ening of the 'tail,' while the specimens were 

 lighter in color, some bearing a perfect I'esem- 

 blance to those that fly in August, near Anti- 

 och and Jerusalem. On the other hand, the 

 pupa subjected to cold gave out butterflies 

 which resembled the Swiss and German forms 

 emerging from hybernated chrysalids. The ex- 

 periments were numerous and confirm the 

 earlier results obtained by Weismann, W. H. 

 Edwards, Merrifield and others. 



Dr. Standfuss is a neo-Lamarckian, believing 

 that, as the result of his experiments, seasonal 

 and local varieties or species are the result of 

 direct changes in the environment — a logical 

 conclusion from the facts. And if this is the 

 case in the laboratory it logically follows that it 

 must be so in nature, especially where isolation 

 occurs. His observations afford him proof of 

 the inheritance of acquired characters. He 

 states that the results of his experiments on the 

 effects of change of temperature render it im- 

 possible to bring them into harmony with the 

 views of Weismann, and he is in accord with the 

 conclusions of Eimer as to the direct influence 

 of the environment and of the inheritance of 

 acquired chai'acters in species-building. He 

 thinks that natural selection is limited in its 

 operation, many species having originated and 

 become established without its aid. Finally, he 

 gives us the following definition of the idea of 

 a species: "Species are groups of individuals 

 which, through the direct influence of certain 

 factors of the external world, have diverged 

 so far from the nearest allied types that they 

 can no more cross with these in their sexually 

 developed forms ; that the completely de- 

 veloped offspring resulting from this crossing, 

 should it occur, are absolutely incapable of 

 breeding with one another." 



It is to be hoped that an English translation 

 of this important work may be published, so as 

 to infuse a more scientific spirit into the minds 

 of the many who are interested in the collection 



