482 



NA TURK 



[October 21, 1909 



In so far as there is any positive declaration to be 

 found in the volume the authors may be classified 

 with the " mutationists." They are at great pains, in 

 fact, to define their precise position as members of 

 that school "of which Bateson, de Vries, Kellog, and 

 T. H. Morgan appear to be adherents " (p. 26). They 

 state further that, " like Darwin," they " welcome all 

 factors which appear to be capable of effecting evolu- 

 tion " (p. 27). What these factors are beyond natural 

 selection (to which they assign some value) it is not 

 quite easy to gather from the present work. Isola- 

 tion, correlation, variation, and heredity have been 

 considered very seriously by all evolutionists from 

 Darwin down to the present time, and it cannot be 

 said that Messrs. Dewar and Finn have shed any new 

 light on these subjects. They tell us (p. 387) that 

 species are made by 



" the inherent properties of protoplasm and the 

 laws of variation and heredity. These determine the 

 •nature of the organism; natural selection and the 

 .like factors merely decide for each particular organism 

 ■whether it shall sur\'ive and give rise to a species." 



This will seem to the render who is not a " muta- 

 tionist " to be very like pure Darwinism with a dash 

 •of " inherent properties of protoplasm " thrown in. The 

 introduction of "biological molecules," which are 

 defined (pp. 157-9) ^s the units of which the germ 

 cell is composed, may be considered as the substitu- 

 tion of a vague conception for the very definite 

 mechanism which has been introduced into the theories 

 of heredity associated with the names of Darwin, 

 Herbert Spencer, Weismann, Mendel, and others. One 

 e.xample of the use of this conception will suffice to 

 show its vagueness : — 



_ " Thus the phenomena of ' mimicry ' and ' rever- 

 sion ' are, we believe, due to the fact that in the 

 ■fertilised egg of both the pattern and its copv a similar 

 arrangement of biological molecules obtains. If we 

 regard the sexual act as resembling in many respects 

 a chemical synthesis, the phenomenon need not sur- 

 prise us " (p. 293). 



The reasons for associating mimicry with reversion 

 •and se.xual reproduction are not very obvious, even 

 from the authors' own point of view. Dealing with 

 the first set of phenomena only, if the " explanation " 

 •means that in a mimic and its model the similarity 

 ■of colour and pattern is due to an identity either of 

 physical structure or chemical constitution, or of both, 

 it is untrue in fact. If it means that the resemblance 

 ■has arisen because the units (i.e. " biological mole- 

 cules ") of which the ovum is in each case composed 

 give rise to a similarity of colour and pattern on 

 ■development, this appears to be a mere paraphrase of 

 the description of the facts and no explanation at all. 



It is to be regretted that Messrs. Dewar and Finn 

 have made this aggressive incursion into the domain 

 of biological theory. They are favourably known as 

 popular writers on Indian ornithology and other 

 natural-history subjects. Although in the present 

 volume none of the objections brought against natural 

 selection are new in principle, it must be placed to 

 the credit of the authors that, unlike so many of the 

 earlier critics of Darwin's work, they are able to give 

 NO. 2086, VOL. 81] 



a certain number of illustrations derived from personal 

 observation and experience. But the work as a whole 

 will not add to their reputation ; with the majority of 

 readers it will probably have the reverse effect. If the 

 general object of the book is simply to emphasise the 

 point that the theory given to science by Darwin and 

 Wallace need not arrest further research in the domain 

 of bionomics, there will be a very general unanimity 

 among workers of all schools as to the soundness of 

 their contention. But if the authors attribute any 

 neglect, real or imaginary, of the study of bionomics 

 to the direct influence of the teachings of Darwin and 

 Wallace and their followers, they are inverting the 

 truth. No greater stimulus was ever given to re- 

 search in this domain than that given by the theory 

 of natural selection. Any neglect with which English 

 biologists can be charged is due to their ignoring and 

 not to their acceptance of the teachings of the founders 

 of that theory. R. Meldola. , 



THE GEOGRAPHICAL DISTRIBUTION OF 

 LEPIDOPTERA. 

 Die geographische V'erbreitiing der Schmcttcrlinge. 

 By Dr. Arnold Pagenstecher. Pp i.x + 451. (Jena : 

 G. Fischer, 1909.) Price u marks. 



THE author of this work is one of the older German 

 entomologists, who has been workingjr for many 

 years in the formation of a collection of Lepidoptera, 

 and has published many v-aluable lists and monographs 

 of the species found in various limited regions. He 

 has now utilised his materials in a work which cannot 

 fail to be interesting, not only to entomologists, but 

 also to all naturalists who direct their attention to the 

 numerous problems connected with the present geo- 

 graphical distribution of animals over the surface of 

 the globe. 



Dr. Pagenstecher remarks that the geographical 

 distribution of Lepidoptera, like that of plants, is 

 closely connected with certain physical and organic 

 factors. The most important physical factors are (i) 

 soil ; (2) temperature and light ; (3) moisture ; (4) atmo- 

 spheric conditions. The first portion of this work is 

 therefore devoted to general observations on the geo- 

 graphical conditions of the continents, and the in- 

 fluence of mountains, desert or fruitful plains, the 

 neighbourhood of rivers and seas, continental and 

 oceanic islands, &c., on distribution. The influence of 

 temperature, moisture, atmosphere. Sec, is then briefly 

 described; then vegetation, carnivorous habits, com- 

 mensalism, &c. This is followed by sections on the 

 distribution of Lepidoptera as affected by altitude, 

 notes on migration, cosmopolitan species, and season- 

 dimorphism and local variation. After this, the organic 

 (physiological) factors of the subject are discussed, 

 with special reference to former geological and climatic 

 conditions, and some reference to fossil Lepidoptera. 

 After some remarks on structure, and on the eaemies 

 of Lepidoptera, the section concludes with a sum- 

 mary of the Macro-lepidoptera of Central Europe 

 (1626 species, according to Lampert), and a table of 

 the species of Papilio found in the more important 

 districts of the world. 



The second section of the work is devoted to the 



