364 



NA TURE 



[February 17, 1898 



modern views on beauty of the female form, occupy the 

 next section. , 



The average weight of the new-born infant, the greater 

 decrease in weight during the -first few days of the male 

 than the female, and of the first-born than the children 

 of multiparae, along with the subsequent daily increase, 

 is given accurately and in an interesting and compre- 

 hensible style. 



Although adopting •w€\^\. fauie de tnieux as a method 

 of comparing brains, the fact that the intellectual qualities 

 of that organ do not vary directly with its mass is re- 

 cognised, and illustrated by reference to individual cases. 

 Unfortunately, when comparing the results of various 

 observers, no statement is made as to which, if any, 

 membranes are included with the nervous substance. 



The book, admirably adapted for students acquainted 

 with anthropometric methods, comprising many original 

 observations, deals mainly with measurements and 

 weights. The absence of instruction as to how they are 

 obtained, detracts from its value to beginners ; while the 

 pathological and anatomical details scarcely recommend 

 It for popular instruction. 



Beschreibung der Hauptmethoden, welche bet der 

 Bestiminung der Verbrennungswdrme iiblich sitid. 

 By W. Longuinine. Pp. 112, with 4 copper-plates 

 and 21 figures, (Berlin: R. Friedlander und Sohn, 

 1897.) 

 This excellent work had already been printed in 

 Russian when Berthelot's "Traite pratique de Calori- 

 metrie chrmique" appeared. The German translation 

 may, however, be welcomed, because its scope differs 

 considerably from that of Berthelot's book. The estima- 

 tion of heat of combustion is alone dealt with by 

 Longuinine, the rest of thermo-chemistry being left 

 untouched. One of the results of discussing only a 

 part of a subject is that, as far as it goes, this book 

 is remarkably complete. Besides a full description of 

 the calorimetric bomb and the precautions to be ob- 

 served in its use, an account is given of the older 

 methods of estimating the heat of combustion, which 

 are still used to some extent, owing to the high price of 

 Berthelot's bomb. Under certain conditions, duly set 

 forth in the text, these old methods give exact results. 

 The illustrations are capital, though unfortunately not 

 drawn to scale, and the whole volume is handsome. By 

 some strange mischance, it is not furnished with either 

 an index or a table of contents. 



Cheltenham as a Holiday Resort. Part I . The Neigh- 

 bouring Hill-Country. By S. S. Buckman, F.G.S. 

 Pp. 100. (Cheltenham : Norman, Sawyer, and Co., 

 1897.) 

 The geology and archseology of Cheltenham and the 

 neighbourhood are described in this book in a way which 

 will induce the reader to make further inquiries into the 

 why and the wherefore of the interesting characteristics 

 referred to. The book will add to the enjoyment of 

 ramblers in the country around Cheltenham, and will be 

 of special value to those who visit the district in search 

 of scientific information. The author has himself made 

 investigations of Cotteswold geology, and his book con- 

 tains the results of original observations as well as 

 references to the work of others. 



Nature's Diary. Compiled by Francis H. Allen. Eight 



photogravures. (London : Gay and Bird). 

 On the left-hand pages are literary extracts, chiefly from 

 Thoreau ; on the right, blank paper for the events of the 

 natural year, with here and there a printed note. The 

 naturalist who uses the book must give it all its value. 

 He would do much better to buy a note-book and a copy 

 of Thoreau's " Walden." This is a book for show and 

 not for use. The eight photographs from nature are 

 capital. L. C. M. 



NO. 1477, VOL. 57] 



LETTERS TO THE EDITOR 



[ The Edi/or does itot hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he tindertaice 

 to return, or to correspnnd with the writers of, rejected 

 vranuscripis intended for this or any other part of NATURE. 

 No notice is taken of anonymous cotnmunications.'\ 



Protective- and Pseudo-Mimicry. 



I HAVE just been reading the presidential address to the 

 Entomological Society on the subject of mimicry, and one or 

 two statements with regard to mimicry among the Heterocera 

 seem to me to stand in need of correction. It is stated on the 

 authority of Colonel Swinhoe that Teracolus etrida is accurately 

 mimicked by the geometer Abraxas etridoides, and that this 

 supports his contention that the species of Teracolus are 

 protected. 



I described Abraxas etridoides from a single specimen taken 

 on the Palni Hills, South India, by M. Elwes, pointing out its 

 resemblance to the Teracolus, which also occurs in South India, 

 This was quite enough for such an ardent student of mimicry as 

 Colonel Swinhoe to base the above statement on, without 

 knowing any more of the species, and probably without ever 

 having seen it, the type being in a private collection. I have, 

 however, lately received more specimens, and been able to learn 

 its habits from collectors on the Palnis, where it rests in damp 

 woods during the day on the plateau, as is the habit of the genus, 

 whilst the Teracolus does not occur on the hills, but flies in the 

 hot sun of the plains 6000 feet below ; the fact being that all 

 the species of the genus Abraxas secrete acrid juices and are 

 distasteful, whilst Teracolus is not protected. 



Again, it is stated that Danaid butterflies are mimicked by 

 three genera of the Chalcosia group of Zygcenidce. These again 

 secrete strong acrid juices, as does the whole family to which 

 they belong, and they are so distasteful that hardly any other 

 animal will touch them ; their habits, too, are extremely dif- 

 ferent from those of butterflies, and no one who knows them in 

 life could possibly believe in protective mimicry between the 

 two groups. The Chalcosias sit about on tree trunks, but are 

 very easily disturbed, when they fly with an extremely wavering 

 flight for a short distance and then settle again. The only excep- , 

 tion in this habit known to me is the Papilio-shaped genus Histia, 

 which flies high over forest trees backwards and forwards with 

 wavering flight, resembling that of the Vapourer Moth in our 

 London squares, and looking so unlike butterflies that not even, 

 the veriest tyro could mistake them, besides being about one- 

 third the size of any Papilio. Both these cases, therefore, will, 

 I think, have to be relegated to the rapidly swelling ranks of 

 museum-made mimicry. 



Protective mimicry entirely depends on community of habit, 

 and it used to be considered that accurate field observations 

 were necessary to establish it. Now that it has been degraded 

 to the matching of specimens in a drawer like ribbons in a shop, 

 being a nice easy subject to philosophise on and entailing a 

 minimum of work, it has lost all claim to serious consideration. 



February 8. G. F. Hampson. 



Oat Smut as an Artist's Pigment. 



The deep brown or sepia-coloured spore dust often seen on 

 cereals, and arising from the presence of a fungoid growth, is 

 sufficiently rich in colour to become useful as a pigment for the 

 artist. The colour obtained from smutty oats, for example, is 

 of a deep rich umber shade, sometimes approaching to sepia in 

 tone. Satisfactory experiments were made regarding its fast- 

 ness to light and atmospheric influences. Specimens of the 

 pigment painted on paper as a water-colour were exposed to 

 direct sunlight for several months ; and after this rather severe 

 trial, they were compared with unexposed duplicate specimens. 

 Little change in the appearance of the colours was apparent. 

 With mild diffused daylight — such as that of an ordinary, well- 

 illumined room — the colour remains quite fast and unaltered. 

 Experiments were made on a small scale with oat smut pig- 

 ment, and the results seemed highly satisfactory. Several 

 grams of the dry spore dust were collected from smutty oats, 

 and it was found that twelve heads of such oats yielded six 

 grams of the brownish-black dust. This powder, being of a 

 dry and light nature, had first to be moistened with a few drops 

 of alcohol, then mixed with gum and water to form a water- 

 colour pigment. In its deepest tones it is of a fine sepia shade, 

 deepening to a brown-black. On diluting with water or Chinese 



