336 



NATURE 



[May 19, 1 9 10 



quarters. Some of the staunchest upholders of 

 natural selection, including Wallace himself, look 

 askance at the theory which seeks to explain certain 

 features of colouring and other ornamentation in male 

 animals as the result of female preference. Here 

 also Weismann ranges himself unhesitatingly on the 

 side of Darwin. Sexual selection is to him a real 

 and active transforming force, as demonstrable as 

 natural selection itsplf, and passing into the latter 

 by an easy transition. A specially interesting section 

 of the present essay deals with the scent-producing 

 organs of male Lepidoptera, the perfume distributed 

 from which is now known in very many cases to be 

 as agreeable to the human perception as it presum- 

 ably is to that of its possessors or their mates. Weis- 

 mann 's own ancillary theory of germinal selection, 

 suggested to some extent by Roux's conception of the 

 "struggle of parts," is here lucidly expounded. 

 Whether the theory be accepted or not — and many, 

 it must be admitted, have found it unconvincing — 

 there is no doubt that it would account for many facts 

 at present not easy of explanation. 



(2) The second treatise is of a different character. 

 It contains a detailed account of elaborate experiments 

 on the removal and transplantation of the primary 

 sexual organs in the larva of Lymantria dispar, com- 

 monly known as the "gipsy-moth." Meisenheimer 

 has succeeded, by the help of the galvanic cautery, in 

 destroying the reproductive glands in larvae of both 

 sexes at various periods of growth, beginning with 

 the earliest stage after emergence from the egg. In 

 partly-grown larvae he has been able to transplant 

 the male primary reproductive organs into the body of 

 a female, and vice versa. As principal results of his 

 experiments he considers himself to have proved the 

 inability of the reproductive organs, as distinct from 

 mere sex-characters, for regeneration ; and also the 

 absence of any formative stimulus for secondary sex- 

 characters, emanating from the primary sex-organs 

 themselves. A transplanted ovary is shown to have 

 no impeding effect on the development of the male 

 reproductive apparatus, while the ovary itself can 

 reach its fully mature condition when artificially in- 

 serted into the body of the male. The regeneration 

 of sex-characters, where this takes place, is entirely 

 unaffected by the absence of the primary sex-organs 

 of the individual concerned, or by the presence of 

 those of the opposite sex. The conditions obtaining 

 in hermaphrodites naturally occurring among the 

 Articulata are similarly adverse to the theory of a 

 special formative stimulus for the secondary sexual 

 characters. Meisenheimer is, of course, well aware 

 that the experimental evidence derived from verte- 

 brates seems, prima facie, completely at variance with 

 his own results ; but he adduces much ingenious argu- 

 ment with the purpose of showing that the " internal 

 secretion " of the testis and ovary, which is certainly 

 a reality, has nevertheless no such specific influence 

 on sex-characters, whether somatic or psychic, as has 

 been supposed. It is, according to him, entirely a 

 matter of enhanced or impeded exchange of material 

 (Stoffwechsel). Metabolism is partially checked by 

 castration, and can be restored by the artificial re- 

 NO. 2 1 16, VOL. 8^} 



introduction of generative products, not necessarily of 

 the same species. But this metabolism is not speci- 

 ally concerned with the sex-apparatus or secondary 

 characters, and any effect it may have thereon is 

 incidental and not essential. The author's facts are 

 undoubtedly striking, and his criticisms of adverse 

 views are weighty. But his argument as regards 

 vertebrates is not entirely convincing. 



F. A. D. 



OUR BOOK SHELF. 



Metalography (Printing from Metals). Being a full 

 consideration of the Nature and Properties of Zinc 

 and Aluminium, and their Treatment as Piano- 

 graphic Printing Surfaces. By Charles Harrap. 

 Pp. xvi + 170. (Leicester: Raithby, Lawrence and 

 Co., Ltd. 1909.) Price 35. net. 



This treatise professes to be a'texV-book on the sub- 

 ject of printing from metal plates instead of stone, 

 and is addressed to the lithographic trade. The term 

 " metalography " is a word invented to specify this 

 particular form of printing as distinct from '* metallo- 

 graphy " as used by metallurgists in a general sense. 



Although metal has been in use with more or less 

 success during the past century, it is evident that it 

 is fast coming into more general demand. Zinc was 

 first used, and is still used very largely, but aluminium 

 has more recently been employed as the basis for 

 taking or holding the design to be printed from. The 

 readiness to which either metal lends itself in bending 

 or curving has in turn suggested the manufacture of 

 printing machines of a rotary character, and the 

 result is that there has been a remarkable development 

 in the presses used in producing printed work by the 

 lithographic method. 



For some classes of work the stone is still pre- 

 ferred, and probably better results can be obtained 

 from this material in some instances ; but if the ques- 

 tion of first cost of stone as compared with metal 

 plates is to be studied, the latter are the more 

 economical. Again, the question of space occupied 

 and the great weight of stones for both storage and 

 carriage must be considered. As already indicated, 

 the introduction of metal plates has allowed more 

 scope for the machine-builder, which has quickened 

 and cheapened the output. With the ordinary litho- 

 graphic stones, which must be printed from the 

 " flat," it was hardly possible that the old forms of 

 presses could be much improved upon. 



One other important development has been the 

 introduction of the rotary off-set presses by several 

 manufacturers, which may be used in connection 

 with one or more colours in printing. Either zinc or 

 aluminium plates may be used, and these are fastened 

 round a cylinder, which gives its impression or off- 

 set to another cylinder fitted with a rubber sheet or 

 blanket. The paper to be printed is then conveyed by 

 grippers to a third cylinder, which in motion receives 

 its impression from that which is covered by the 

 rubber. 



Very^ good results are given on cards, or even rough 

 paper, without previous dampening of either material ; 

 this obviates the employment of glazed or calendered 

 surfaces, which is a decided advantage. The finished 

 sheets are delivered automatically and the printed 

 face upwards, so that the work can be easily watched 

 in course of production. Such machines as these will 

 produce 1500 or more copies per hour, fed in singly by 

 hand, but the output may be considerably increased 

 by adop>ting an automatic feeder. 



The author has treated the whole subject in a very 

 practical manner, and his long experience as a 



