616 
(Lockwood) ; The Coming Transit of Venus, by William Peck 
(R. Symon); The Horse in Motion, by J. B. D. Stillman 
(Triibner) ; Bibliotheca Orientalis, by C. Friederici (Triibner) ; 
Contributions to the History of the Development of the Human 
Race, by Geiger (Triibner). 
THE additions to the Zoological Society’s Gardens during the 
past week inclade a Bonnet Monkey (Macacus vadialus 9) from 
India, presented by Mr. W. T. Fremlin; a Two-spotted Para- 
doxure (Nandinia binotata) from West Africa, presented by Mr. 
A. N. Blyth; a Rufous Rat Kangaroo (/Zypsiprymnus rufescens & ) 
from Australia, presented by Mr. C. Caravossi ; two Cockateels 
(Calopsitta nove-hollandie § 2) from Australia, presented by 
Mr. W. C. Atkinson ; a Common Raven (Corvzs corax), British, 
presented by Mr. H. E. Langton ; a Roseate Cockatoo (Cacatua 
rvoseicapilla) from Australia, presented by Mrs. Ramsay; a 
Lanner Falcon (Falco /anarius), from East Europe, presented 
by Mr. J. E. Harting, F.Z.S. ; a Common Night Heron (ycdi- 
corax griseus), European, presented by Mr. H. D. Compton; a 
Lesser White-nosed Monkey (Cercopithecus petaurista 3) from 
West Africa, a Cabot’s Horned Tragopan (Ceriornis raboti & ), 
from South-West China, deposited ; a Silvery Gibbon (Hy/obates 
leuciscus) from Java, a Mongoose Lemur (Lemur mongoz 3), a 
Red-fronted Lemur (Lemur rufifrons 6), two Grey-headed 
Love Birds (Agafornis cana 2 2) from Madagascar, a Squirrel 
Monkey (Chrysothrix sciurea), a Squirrel Monkey (Chvy- 
sothrix, sp. inc.) from Guiana, two Rufous-tailed Pheasants 
(Zuplocamus erythropthalmus 8 9) from Malacca, a Wheatear 
(Saxicola enanthe), a Meadow Pipit (Anthus pratensis), a Red- 
start (Phenicura ruticil/a), British, a Burchell’s Zebra (Equus 
burchelli 6) from South Africa, pu-chased ; an Eland (Oveas 
canna 8), two Short-headed Phalangers (Belideus breviceps), a 
Squirrel-like Phalanger (Belideus sciureus), four Stender Ducks 
(Anas gibberifrons), two Common Cormorants (Phalacrocorax 
carbo), bred in the Gardens. 
OUR ASTRONOMICAL COLUMN 
THE OBSERVATORY OF TRINITY COLLEGE, DUBLIN.—Th® 
fourth part of ‘‘ Astronomical Observations and Researches mad 
at Dunsink”’ has just appeared under the editorship of Mr, J- 
L, E. Dreyer. It contains the results of about 1140 observations 
of 321 red stars, chiefly taken from Scbjellerup’s Catalogue, 
made with the meridian-circle of the Dunsink Observatory, the 
object-glass of which has an aperture of 6°38 inches, the instru- 
ment being the work of Piston and Martins of Berlin. The 
observations were commenced by Dr. Copeland in July, 1875, 
and continued by him up to the end of March, 1876. Mr. 
Dreyer commenced observations in September, 1878, and the 
series was finished in November, 1880. As ‘far as possible, it 
has been the object to secure four complete observations of each 
star. The separate results are printed, with the corresponding 
daies and estimates of the maguitudes of the stars which have a 
particular interest from the fact of so many of the red stars being 
variable. The Dublin observations show this to be the case in a 
striking degree, and not only is there variation in the brightness 
of many of the objects, but it is hardly possible to doubt that 
they establish changes of colour from time to time in some of the 
stars. Thus we find No. 5 (Schjellerup) was wzte on November 
14, 1875, and deep orange three months later. No. 143 was 
considered orange on February 28, 1876, but showed x0 colour 
on March 19; in March, 1880, it was again orange. No. 186 
had no colour on April 30, 1880, but was deep orange on June | 
Io following; and there are a number of similar cases, too 
many, it would appear. to allow of their being attributable to 
varying conditions of atmosphere. 
The observed positions of the 321 stars are formed into a 
general Catalogue for 1875°0, with the corresponding precessions, 
which will have much value in the study of the proper motions 
of the red stars. 
THE OBSERVATORY OF Moscow.—Prof. Bredichin has 
issued the first part of vol. viii. of Annales de Ll’ Observatoire de 
Moscou, which in addition to meridian observations, contains a 
continuation of his researches upon the tails of comets, the 
NATURE 
[April 27, 1882 
present publication including the comets 1881 6 and ¢, and the 
fourth or great comet of 1825. Prof. Bredichin has reprinted 
the long series of physical observations on the latter body made 
by Dunlop at Paramatta N.S.W., which originally appeared in 
Brewster’s Edinburgh Journal of Science, 1827, and which have 
been a good deal overlooked, that periodical, on the continent at 
least, not being easy of access. Dunlop’s drawings are repro- 
duced, and there are several figures of the two bright comets of 
1881. With regard to his investigations generally, Prof. Bredi- 
chin concludes: ‘* Mes recherches sur toutes les Cométes, dont 
les observations j’ai pu trouver dans la littérature astronomique 
(36 cométes) me mettent maintenant en état de caleuler d’avance 
pour chaque grande Comete qui paraitrait les positions et Ja 
figure de ses queues de tous les trois types. II est evident que la 
quantité rélative des substances caudales de différents types ne 
peut pas étre déterminée d’avance, et par conséquent c’est seu- 
lement l’observation qui pourra nous montrer et la clart¢ rélative 
des types et l’absence possible de tel ou tel d’entre eux. Mais 
en tout cas, les positions et la forme générale de celle des queues, 
qui deviandra, accessible a la visio1, seront en accord avec ses 
positions et sa figure calculées d’ayance.” 
THE PRESENT ComMET.—The following positions for Green- 
wich midnight ate from the elements published last week. On 
April 16 the calculated place was in error — 7s. in R, A, and — 2" 
in declination, but the errors will be increasing. 
R.A Decl. Log. distance from 
} | ae Earth. Sun. 
May 2 20 52°4 +69 53 9°9904 ... 0'0793 
4 21 22°6 71 40 99818 ... 0°0632 
6 21 59°5 73 9 9°9740 ... O'0461 
ees eae 74 10 ... 99671 ... 0°0280 
TO) ee 23) S210: +74 35 ... 9°9610 ... 00087 
The perihelion distance in the orbit referred to which depends 
on observations to April 6 is 0°0560; M. Bigourdan, from 
observations at Paris to April 11, finds it 0°0602. 
GEOTROPISM AND GROWTA* 
IF the punctum vegetationis of a root is removed by a transverse 
section, the root loses more or less completely the power of 
curving geotropically downwards when placed in a horizontal 
position, This curious experiment was originally made by 
Ciesielski, and has been confirmed by the observations described 
in ‘*The Power of Movement in Plants” (chap. xi.). The 
theory founded by Mr. Darwin in these observations is that the 
punctum veg. is the part of the root which is sensitive to gravita- 
tion, and that a stimulus is thence transmitted to the region of 
growth where the geotropic curvature takes place. But it is 
evident that the facts are capable of a different interpretation, it 
might be supposed that cutting off the tip of the root acts merely 
as a shock, and prevents the occurrence of geotropism, just as 
any other severe injury might do so. This view has recently been 
brought forward by Wiesner (‘‘Das Bewegungsvermogen 
der Pflanzen,’ 1881, p. 97), and is supported by him with a 
number of experiments on the growth of decapitated roots. The 
results of some of Wiesner’s experiments are given below, the 
figures representing the amount of growth per cent. in twenty- 
four hours :— 
Maize. 
Nermal Roots. Deri 
HS es 41 or as Ico: 52°9 
Peas. 
a RES, 
42°7 n 97 5) 1008 227 
Vicia Faba. 
eee 
90 60 >, 100: 66°6 
Wiesner believes that this difference in growth between the 
normal roots and those of which tips had been cut off is sufficient 
to account for the disturbance in geotropism. It should be 
added that in Wiesner’s experiments geotropism was not so 
completely checked by cutting off the tips of the roots as in those 
given in the ‘‘ Movements of Plants.” 
In the present paper the intervals of time between the ob- 
servations on the rate of growth were shorter than in Wiesner’s 
experiments—namely, about three hours instead of twenty-four 
hours ; the reason for this difference being that geotropic curva- 
* A paper read before the Linnean Society, April 6, by Mr. Francis 
Darwin. 
