Dec. 19, 1878] 



NATURE 



'55 



to examine this near approach more closely, particularly 

 as Bouvard's Tables of Saturn were used for 1879. Ac- 

 cording to Leverrier's Tables, the position of Saturn from 

 Bouvard requires corrections of about + 179s. in Right 

 Ascension, and - o"'4 in Declination; whence, with Le- 

 verrier' s place of Mars the conjunction in right ascension 

 occurs atSh. 37m. G.M.T., and at this time the geocentric 

 difference of declination is i' 29'"'o. The apparent semi- 

 diameter of Mars (taking 9''*45 for the diameter at mean 

 distance) is 4"'46, and the apparent polar semi-diameter 

 of Saturn, 7"*83 ; the horizontal parallaxes, 8'''36 and 

 o"*93 respectively. Hence it is evident that there will be 

 no approach to an occultation. At conjunction the 

 planets will be below the horizon in this country, but will 

 be near the meridian at our Australian observatories ; 

 there, however, the least distance between the south limb 

 of Mars and the north limb of Saturn will, according to 

 the Tables, exceed a minute of arc. Mr. Marth has 

 pointed out that the last close conjunction of Saturn and 

 ^lars took place on April 18, 1817 ; the Berliner Jahr- 

 buch for that year gives the time of conjunction at 7h. 

 M.T. at BerUn, with Mars i' S. of Saturn. 



An occultation of Saturn by Mars, so far as we know, 

 has not yet been put upon record, nor suspected before 

 the invention of the telescope. The earliest mention of 

 a near approach of the two planets is found in the Chinese 

 annals during the latter days of the loth moon, A.D. 27; 

 on this occasion Mars, Jupiter, and Saturn were all situate 

 within about 2° from the bright star Regulus ; and the 

 same annals record that on July 23, A.D. 143, Mars was 

 very near to Saturn. 



BIOLOGICAL NOTES 



Natural Selection among Larval Salamanders. 

 — Every case illustrating survival of the fittest has its own 

 interest, as well as its bearing on general laws. The 

 New England salamanders lay large numbers of eggs 

 attached to water plants, and the larvae are very interest- 

 ing to watch. In a group that was studied recently, can- 

 nibal tendencies soon developed, the stronger eating off 

 the gills of the weaker, at the same time being able to 

 protect their own, within a week or ten days after hatch- 

 ing ; these cannibals were fifty per cent, larger than their 

 brethren, and, soon waxing bolder, they began to swallow 

 them bodily. After ten days of the results of such feed- 

 ing, they were ten or twelve times the size of such weaker 

 brethren as were still left alive. Thus they rapidly de- 

 veloped and passed out of the gill-bearing stage. See 

 Mr. S. F. Clarke, in American Naturalist for September. 



The Muscles of the Mammalian Foot. — Dr. D. J. 

 Cunningham {Jour 71a I of Anatomy and Physiology, 

 October, 1878), after dissecting the manus and pes of a 

 large number of mammals, finds that the typical arrange- 

 ment of the intrinsic muscles of the foot is the same as 

 in the hand, and that this is best seen in certain mar- 

 supials. In these animals the muscles are disposed in 

 three layers (i) a plantar layer of adductors ; (2) an inter- 

 mediate layer of short flexors ; and (3) a dorsal layer of 

 abductors. Deviations from the type may take place by 

 suppression or by fusion of certain elements of the dif- 

 ferent layers. Fusion of the members of the intermediate 

 and dorsal layers is very common. The presence of an 

 opponens muscle is not accounted for in the foregoing 

 disposition. When present Dr. Cunningham regards it 

 as derived most commonly from the short flexor, but in 

 many of the carnirora it proceeds from the plantar layer. 

 Further, it is found that in many animals the relation of 

 the intrinsic muscles to the metatarsal bones, both as 

 regards their origin and position, corresponds with tran- 

 sitory conditions in the foot of the human embryo. The 

 adult dog agrees exactly with the first stage of the human 

 foetus in the relation of the intrinsic pedal muscles to the 



metatarsals ; the bones are closely compressed together,, 

 and the muscles are entirely plantar in position. 



Sensitive Organs in Asclepiadace^.— Robert 

 Brown gave it as his opinion, based on experience, that 

 fertilisation in this family of plants depends largely upon 

 insect agency. Dr. J. G. Hunt has recently published 

 observations on Stapelia asterias, whose flower has an 

 extremely disagreeable and animal odour, which appears 

 to attract many flies. Under observation flies were seen 

 eagerly applying their tongues all over the petals and 

 essential organs, apparently eating, with an almost intoxi- 

 cating reUsh, the excretion covering those parts. This 

 banquet was indulged in with safety until their tongues 

 came in contact with one of five black spots situated near 

 and alternate with the stamens, when, with amazing^ 

 quickness, the fly was seized and firmly held by the 

 tongue— a hopeless prisoner. Now a struggle com- 

 menced, and if the fly was small and not vigorous, he 

 was retained ; if large and strong he escaped, dragging 

 away the black spot and also the pollen-masses, two of 

 which are attached to each trap. The adhesion of the 

 fly's tongue is not caused by any viscid liquid, but by a 

 capital pair of blades, which, when touched lightly by a 

 fly, or even a hair, close instantaneously, and secure the 

 object. Two species of Asclepias have been examined by 

 Mr. Edward Potts, and in these he finds that each anther 

 has a pair of sacks or cases in which the pollen masses 

 are suspended so as to make their withdrawal easy. They 

 are closely adherent to the stigma. The sensitive glands 

 are placed in shallow depressions upon the perpendicular 

 columnar ridges of the stigma. The fact of the removal 

 of the pollen masses by insect agency is well known ; the 

 question to determine was whether the glands had any- 

 thing to do with the removal. Mr. Potts caught house- 

 flies and held them by their wnngs above the flowers, 

 allowing their feet to scramble over them. Almost imme- 

 diately one or more of these would become ornamented 

 with groups of the glands and pollen-masses, which clung 

 so closely that their later struggles and rubbings failed to 

 detach them. When separate hairs were directed on to a 

 gland, the latter instantly contracted and clung to the 

 hair, tearing itself loose from the stigma, and carrying 

 away the pollen masses with it. On one of the 

 species of Asclepias Mr. Potts noticed three flowers 

 which, in addition to its own complete anthers, 

 had one other sensitive gland and its attached pollen- 

 masses, inserted under the edge of a normal anther, 

 and against the sloping lower surface of the stigma. 

 The development of these adventitious pollen-masses, 

 was traced tiU they put forth a profusion of pollen- 

 tubes into the stigma, and the ovaries began to in-^ 

 crease in size. Dr. Asa Gray mentions self-fertilisation 

 as occurring in this genus by a similar growth of bundles 

 of pollen-tubes penetrating the stigma at its lower extre- 

 mity. But here in the presence of the foreign pollen- 

 masses none of the home-grown ones had put forth pollen- 

 tubes. It is conjectured that the maturity of the pollen- 

 masses is reached so late that the stigma of the same 

 flower is frequently unsusceptible. But if the pollen- 

 masses from earlier flowers are removed by insects' and 

 lodged upon another just opened, they develop pollen- 

 tubes, and cross-fertilisation ensues. Thus the sensitive 

 glands are not for capture of insects, but to favour 

 cross-fertilisation. {Proceedings, Acad. Nat. ScL Phila- 

 delphia, 1878). 



The Inhalation of Phosphuretted Hydrogen.— 

 Dr. T. B. Henderson, of Glasgow ( [ournal of Atiatomy 

 and Physiology, October, 1878), has investigated the 

 physiological effects of the inhalation of phosphuretted 

 hydrogen gas, by inclosing an animal in an air-tight 

 chamber of known capacity, and subsequently introducing 

 into this a given quantity of the gas. In the first experi- 

 ment a strong rat was placed in an atmosphere consisting 

 almost entirely of phosphuretted hydrogen, and death. 



