Nov. 28, 1878] 



NATURE 



75 



lowing formulae, where L is the east longitude from 

 Greenwich, / the geocentric latitude, and / the Green- 

 wich mean time of beginning or ending, according as the 

 upper or lower sign is employed : — 



Cos.a;= + 109 •0051 —[2 •34283] sin. /+ [1 '98006] cos. /cos. (L - 15' i5"9). 

 /=iih. 10m. ^S'gs. T [i"58i54] sin. Mf+ [3-i6228] sin. /. 



— fs 95668] COS. /. COS. (L — 126* 35''7). 



Transits of Mercury. — Prof. Holden has published 

 an " Index-Catalogue of Books and Memoirs on the 

 Transits of Mercury," which he had prepared to aid him 

 in a search for records of the physical phenomena which 

 have been observed at such transits. The list is not quite 

 a complete one, the publications of observatories not being 

 included, but there is little inconvenience in the omission, 

 as such observations and memoirs can be found by refer- 

 ence to the volumes for transit years, and Prof. Holden 

 gives a list of the dates of all the transits of Mercury so 

 far observed. Catalogues of this description must prove 

 most serviceable to the student and to every one who 

 has occasion to consult the general literature of an 

 astronomical subject, and we hope the American astro- 

 nomer may find leisure to continue them. Reference has 

 already been made in this column to his very valuable 

 "Index-Catalogue to the Literature of iSebulas and 

 Clusters," &c., forming No. 311 of the "Smithsonian 

 Miscellaneous Collections." The publication above men- 

 tioned forms No. i of "Biographical Contributions," 

 edited by Justin Winsor, Librarian of Harvard University. 

 The copy before us is republished from the Bulletin of the 

 library for October, 1878. 



Biela's Comet and Jupiter in 1794. — It will be 

 remembered by those who may have interested them- 

 selves in cometary astronomy, that between the first 

 appearance of Biela's comet in 1772, and the next return 

 at which it was observed, in the latter part of 1805, the 

 elements had undergone alterations of a magnitude that 

 occasioned doubts as to the identity of the comets, not- 

 withstanding the general similarity of orbits, Bessel 

 pronouncing against it, while Gauss pointed out that 

 more than one revolution must have been accomplished 

 in the interval, so as to admit of the comet having 

 approached one of the larger planets and thereby expe- 

 rienced perturbation to account for the differences in 

 several of the elements. The disturbing body is now 

 known to have been the planet Jupiter, and there has 

 been no difficulty in fixing the epoch when the comet' s 

 motion was most deflected, but we do not recollect to 

 have seen the particulars of the near approach of the two 

 bodies stated in any astronomical work. Starting from 

 the final elements for perihelion passage in 1806, deter- 

 mined in the masterly investigation of the late Prof. 

 Hubbard of Washington, it appears that neglecting plane- 

 tary perturbation in the interval, the comet would have 

 made its nearest approach to the planet at the beginning 

 of June, 1794, when their distance was less than 0*47 of 

 the mean distance of the earth from the sun. The fol- 

 lowing distances have been similarly obtained : — 



Distance Distance 



' ^794 from 1794 from 



Jup'.ter. Tupiter, 



March 2 0*654 May 31 0-469 



April I 0-562 June 15 0*473 



May I 0-496 „ 30 0-488 



II 16 0-477 



At the time of closest approximation, the heliocentric 

 longitude of the comet was about 269° 40' and the latitude 

 + 4° 25'. 



BIOLOGICAL NOTES 



Gall-making Insects.— At the St. Louis meeting 

 of the American Association Prof. C. V. Riley read 

 \ P^P^^ °° t^6 gall-making Pemphigince. He said 

 that the life-history and agamic multiplication of the 



plant-lice {Aphidida) have always excited the inte- 

 rest of entomologists as well as of anatomists and 

 embryologists. The life-history, however, of the gall- 

 making species belonging to the Pemphigince has baffled 

 the skill of observers more than that of any other group. 

 Mr. Riley is about to publish some new biological dis- 

 coveries relating to this family of insects, in connection 

 with a descriptive and monographic paper by Mr. J. 

 Monell, of the St. Louis Botanic Gardens. The paper 

 laid before the Association simply records some of the 

 yet unpublished facts discovered. All of the older 

 writers, in treating of the different gall-producing Pem- 

 phigina of Europe, have invariably failed to trace the 

 life-history of the different species after the winged 

 females leave the galls, and, with few exceptions, have 

 erroneously inferred that the direct issue from the winged 

 females hibernates somewhere. The most recent pro- 

 duction on the subject is a paper published in the present 

 year in Cassel, by Dr. H. F. Kessler, which is entitled 

 the "Life-History of the Gall-Making Plant-Lice, affecting 

 Ulmus campestris." The author, by a series of ingenious 

 experiments, rightly came to the conclusion that the 

 insects hibernate on the trunk, but he failed to discover 

 in what condition they so hibernate. Led by his pre- 

 vious investigations into the habits of the grape Phyl- 

 loxera, Mr. Riley discovered, in 1872, that some of our 

 elm-feeding species of Pemphigince produce wingless 

 and mouthless males and females, and that the female 

 lays but one solitary impregnated Ggg. Continuing hi« 

 observations, especially during the present summer, he 

 has been able to trace the life-history of those species 

 producing galls on our own elms, and to show that they 

 all agree in this respect, and that the impregnated egg 

 produced by the female is consigned to the sheltered 

 portions of the trunk of the tree and there hibernates — 

 the issue therefrom being the stem-mother which founds 

 the gall-inhabiting colony the ensuing spring. Thus the 

 analogy in the life-history of the Pemphigince and the 

 Phylloxerince is established, and the question as to what 

 becomes of the winged insects after they leave the galls 

 is no longer an open one. They instinctively seek the 

 bark of the tree and there give birth to the sexual indi- 

 viduals, either directly or (in one species) through inter- 

 vening generations. 



Leaf Absorption in Plants. — The earlier experi- 

 menters on this subject, M. Perault, to wit, and Hales 

 (1731), were persuaded that leaves absorbed dew and 

 rain. For over a century the investigations of others 

 supported this view, until M. Duchartre, in 1857, from 

 his experiments, advanced a contrary opinion — that now 

 held by most vegetable physiologists, and commonly 

 taught in our schools. But, strange to say, gardeners, in 

 their every-day operations, adopt a different notion from 

 that prevailing in science. The subject has recently 

 received the attention of the Rev. G. Henslow, who, in a 

 paper read before the Linnean Society (November 7), 

 shows that, while it may be true that, as Duchartre has 

 said, dew is not absorbed by saturated tissues at night ; 

 yet, on the contrary, his (Henslow's) experiments go to 

 prove that absorption does take place at and after sun- 

 rise, when transpiration recommences, and an indraught 

 is caused by the moisture, wherever lingering on the 

 leaves. He further corroborates M. Boussingault's late 

 assertion, that, when leaves are purposely or naturally 

 killed by excessive drought, they then do absorb water, 

 as proved by the balance, or otherwise. 



British Newts.— From an article by M. Ferrand 

 Lataste in the last volume of the Journal of the Soci^td 

 Zoologique de France, it appears that the supposed fourth 

 species of British newt — Gray's banded newt {Ommato- 

 triton vittatus) of Mr. Cooke's " Our Reptiles" — may be 

 altogether removed from the British catalogue. It was 

 first introduced into the British list by Jenjus, in 1835, 

 on the faith of some specimens found in a bottle in the 



