Oct. 1 6, 1879] 



NATURE 



583 



Panama to Valparaiso, by Mr. James Douglas, and an 

 account of a visit to the "Wonderful Rivers of Cambodia," 



by Mr. Frank Vincent. 



Dr. Crevaux, the explorer of French Guiana, is not 

 yet, it seems, coming home, but will attempt to reach the 

 Andes by the I^a or Putumayo, exploring that water- 

 system as he has ah-eady done the Marori, Ozapok, Yary, 

 and Para. 



OUR ASTRONOMICAL COLUMN 

 Biela's Comet.— Even if the earth should encounter 

 an unusual number of meteors on arriving at the descend- 

 ing-node of Biela's comet next month, as some have 

 anticipated, the display is likely to be masked to a 

 ■considerable extent by overpowering moonlight. The 

 earth will reach the node (so far as we can judge of its 

 actual position) on November 27, and the moon will be 

 full on the following day. Remembering that the meteors 

 of 1872 were not generally remarkable for brightness, 

 though there were some notable exceptions, should 

 there be a return of the shower, a large proportion may 

 escape notice. No doubt, however, a strict watch will be 

 maintained during the last week in November. We are 

 not able to judge how near we may be to the meteoric 

 mass which the earth met on November 27, 1872 ; it 

 would arrive at perihelion at the end of December in that 

 year, but we do not know the exact period in which it was 

 revolving. 



It is worthy of note that the effect of the differences of 

 mean anomalies and mean motions when the two nuclei 

 ■of the comet were last observed in J852, would in 1879 

 occasion a difference in the times of perihelion passage to 

 the extent of nearly 3A days, and the mutual distance of 

 the nuclei would be increased to 0075 of the earth's mean 

 distance from the sun, or nearly 7,000,000 miles. 



Between the year 1772, when the comet was first 

 observed, and 1852, when the last observations were 

 obtained, the node had retrograded upwards of 11°, the 

 perturbation being chiefly caused by th." planet Jupiter in 

 1794, 1831, and 1842. 



When we consider the conditions under which Biela's 

 <:omet appeared in 180 J, we are struck with the favour- 

 able opportunity which the repetition of such a case may 

 afford for a precise determination of the solar parallax. 

 On the evening of December 8 in that year the comet 

 -at transit at Greenwich was distant from the earth less 

 than 0-038, and its horizontal parallax was upwards of 

 four minutes J at this time, with a declination of near 24° 

 south, it was rapidly descending below the horizon in 

 iliurope, still it was well observable, and of course 

 ■would have been in a very good position for observation at 

 the Cape of Good Hope. Its appearance also was 

 favourable for accurate observations, which is more than 

 can be said of all comets that have approached near to 

 the earth. Olbers mentions that on this evening when 

 he was observing with Bcssel, the nucleus was very small 

 and defined like a planet, and Gauss at the same time 

 compares it to a star of the third or fourth magnitude, 

 riicre has been no such opportunity since the Cape 

 ' )bserratory was established. 



THE GALLERIES OF THE CUTTING ANTS 



OF TEXAS 

 ]y/T R. McCOOK, the devoted student of insects, has in 

 -^'JL preparation a memoir, which will be looked for 

 vith the mtcnscst interest, resulting from his prolonged 



» investigations into the life-history of the cutting or 

 ; parasol" ants of Texas {Atla/crveits), bidding fair to 

 rival his work upon the agricultural ants. 



First, let us take with Mr. McCook a brief view of a 



denuded surface on a high grassy prairie, covered with a 



fc number of small moundlets of fresh earth-pellets, yet 



without a sign of life, and looking entirely abandoned • 

 over Its surface were seen little heaps of dry twigs and 

 pieces of leaves. But towards evening, hosts of ants 

 hurried out, and formed two long double columns to the 

 top of an overhanging live-oak. The ants in the descend- 

 ing columns all carried above their heads portions of 

 green leaves, whence they derive their popular name of 

 " parasol " ants. The closing of the gates in the morning 

 came to pass thus :— Bits of dry twigs and leaves of 

 various lengths are carried into the gallery, filling it up 

 from half an inch to an inch and a haff below the surface; 

 often the galleries slant inwards, even to 45°; or divide 

 soon. The larger "castes" carry in the refuse; as the 

 hole closes the smaller castes appear. The "minims," 

 in small squads, fill in all interstices with minute grains 

 of sand, and finally the last steals in behind some bit of 

 leaf, and the establishment is closed. The reverse takes 

 place, when outside work is resumed in the evening 

 When the larger forms get out they at first carry away 

 and drop their burdens, and little seems to be accom- 

 plished for a long time. But in a marvellous way there 

 occurs a final rush, by which the gate is opened. The 

 bigger pieces of twigs are evidently regarded as special 

 treasures, and were seen used on several successive days. 

 The use of the smallest castes is thus found ; some remain 

 at only one-sixteenth of an inch long, while the fertile 

 female attains nearly an inch, and the male is three-fourths 

 of an inch long. The interior of the formicary is com- 

 posed of caverns or pockets communicating with the 

 surface and with each other by tubular galleries. The 

 chambers contained masses of very delicate leaf-paper 

 wrought into rude oombs. Some masses were hemispheres 

 in shape, others were arranged in columns two and a half 

 inches high, in contact, along the floor of the chambers, 

 whose dimensions might be nearly three feet by one foot, 

 and eight inches high. Some hung from tree-roots which 

 passed through the chamber. All this material was com- 

 posed of the fibre of leaves reduced to this form within 

 the nest. In each portion of ant-comb the cells were 

 nearly hexagonal, but very varied in size, some being 

 half an inch in diameter, but most of them as minute as 

 one-eighth of an inch. Large circular openings ran into 

 the heart of the mass. Ants of the small castes were 

 very numerous in these cells. The material of the comb 

 was very fragile and perishable. It is supposed by Mr. 

 McCook that the ants feed upon the juices of the leaves, 

 but this waits further confirmation. Some of these 

 chambers are even of very large dimensions ; one of the 

 size of a flour-barrel was seen, being the main cavity of a 

 formicary, in which were found very many winged males 

 and females and larva;. This was situated 669 feet from 

 a tree that stood in the front yard of a house, which these 

 ants had stripped. Mr. McCoo'c took a plan of the 

 underground way traversed by the ants to reach this 

 point ; the course varied very little from a straight line ; 

 two branches had been made to a peach orchard 120 feet 

 distant. Only the small forms appear to take part in the 

 digging, while the larger assist in opening the gates, 

 make the excursions, and do the leaf cutting. The least 

 forms, or minims, assist in opening and closing doors, and 

 taking charge of larva. The minims arc quite ferocious 

 in attack, and gallantly support the large-headed soldiers. 

 The process of leaf-cutting has been so successfully ob- 

 served by Mr. McCook, that it is quite deserving of 

 further notice, which we hop)e soon to give. 



G. T. Bettany 



ROUTES TO CHINA viA AS AM 



•yUE possibility of connecting India with China by a 

 tolerably direct and easy trade route overland is a 

 question of increasing interest to us all, in India and 

 England. Not only would such a route benefit the large 

 valley of Asam, by causing an influx of labour more or 



