Aug. 8, 1872] 



NATURE 



279 



OUR BOOK SHELF 



Description of a Specimen of Bahinoptcra musculns, in 

 the possession of the Boston Society of Natural History. 

 Ry Thomas Dwight, jun., M.D. (Boston Society of 

 Natural History.) 



The eleventh volume of the " Memoirs of the Boston 

 Society of Natural History" contains a descriptive ac- 

 count, by Dr. Thomas Dwight, of the external characters 

 and skeleton of a young razor-back whale, the skeleton of 

 which is preserved in the Society's Museum. This animal 

 was captured alive in October 1870,011' Gloucester, Massa- 

 chusetts, and its skeleton is the best preserved specimen 

 of a large whale in any of the American museums. The 

 animal was 4Sft. long, the flipper was 5 ft. 4 in., and the 

 height of the dorsal fin, measured along the anterior edge, 

 was I ft. 2 in. The baleen was of a very light straw colour 

 anteriorly, whilst further back dark stripes appeared on if, 

 until the hindmost blades were of a uniform dark slate 

 colour. From the very careful description which Dr. 

 Dwight has written of the skeleton, and from the figures 

 given in illustration, there can be no question that the 

 animal is a young example of the fin-whale, which Dr. 

 Gray has rnxneAPhysalns antiquorum, but which is more 

 appropriately named Balcenoptera innscitlus. In some 

 remarks on the classification of the specimen, he refers to 

 the tendency to variation in the forms of the bones 

 exhibited in the skeletons of cctacea, undoubtedly be- 

 longing to the same species, and he agrees with those 

 cetologists who have shown the danger of accepting 

 mere individual variations in the forms of the bones 

 of particular specimens as affording data for establish- 

 ing specific or generic differences. W. T. 



LETTERS TO THE EDITOR 



[ The Editor does not hold hiniself responsible for opinions expressed 

 by his correspondents. No notice is taken of anonymous 

 communications. ] 



Bree on Darwinism 



Permit me testate — though the statement is almost super- 

 fluous — that Mr. Wallace, in his review of Dr. Bree's work, 

 gives wi h perfect correctness what I intended to express, and 

 what I believe was expressed clearly, with respect to the probable 

 position of man in the early part of his pedigree. As I have not 

 seen Dr. Bree's recent work, and as his letter is unmtelligible to 

 me, I cannot even conjecture how he has so completely mistaken 

 my meaning : but, perhaps, no one who has read Mr. V/allace's 

 article, or wlio has read a work formerly published by Dr. Bree 

 on the same subject as Iiis recent one, will be surprised at any 

 amount of misunderstanding on his part. 



August 3 , Charles D.4RWIN 



Ants and Aphides 

 Among other misstatements in Dr. Bree's " Fallacies of 

 Darwinism," so ably criticised by Mr. Wallace in Nature of 

 July 25, occurs the following: — "All the stories about aphides 

 being treated as milch-cows are myths, the result of inaccurate 

 observation" (p. 166). I can personally refute this statement, 

 having on many occasions watched the process. Speaking of 

 the attraction of male emperor moths by a captive female. Dr. 

 Bree observes: — "All this was clearly, and widiout doubt, 

 done by the sense of smell " (p. 209). I, in common with most 

 other entomologists, should much value the evidence on which 

 this very positive assertion rests ; for the explanation of the 

 attraclive power of female insects has hitherto remained a 

 mystery. R. Meldola 



Atmospheric Effect 

 The plienomenon mentioned by Prof. Tyndall as recently 

 occurring at the Bel Alp is not mfrequent at the coast. At 



Folkestone in the month of June last, we saw several more or 

 less striking instances. Some years since I witnessed, while 

 driving, on a summer's evening, between Guildford and Godal- 

 ming, an equally beautiful though different effect. The evening 

 was stormy, and the sun, still some distance above the western 

 horizon, threw its sheaf of rays do^enziuirds from behind a light 

 cloud. In the eastern horizon was a dense, dark thunder-cloud, 

 and upon this was seen a reflection of the opposite horizon, the 

 shadows being absorbed by the dark l.iack ground, while the 

 intervening spaces or rays shone out with a briUiancy con- 

 siderably exceeding that of those in the west. The whole of the 

 circumstances were different from those described by Prof. 

 Tyndall, tliere being, as far as I can recollect, no iipmrd rays 

 from tlie sun, and the rays seen on the cloud being neither 

 convergent nor divergent, but merely parallel, and apparently a 

 complete reflection of those which shot from the sun to the 

 horizon. Their wonderful brightness, as contrasted with the 

 rays of which they were the image, was, no doulit, the effect of 

 contrast upon the almost blank screen on w'nich they were seen. 

 This latter, however, was lighted up to a certain extent by a 

 sort of golden haze, in which the rays shone. The whole phe- 

 nomenon was one of great beauty, and was witnessed by some 

 friends of mine at Guddford at about the same time as I saw it 

 from a point near to Godalming. J. Rand Capron 



Guildford, Aug. 30 



The Carbonic Acid in Sea-water 



\n the Deep-sea explorations undertaken of late years in 

 England, the gases obtained from sea-water at various depths, 

 and under different conditions, have been the subject of investi- 

 gation. As coadjutor in the German expedition to the Baltic, I 

 have been engaged in the analysis of the sea-water gases. There 

 have occurred circumstances which I have thought it desirable to 

 communicate to you with reference to your forthcoming future 

 Deep-sea explorations. 



I muit premise that the expulsion of the sea-water gases was 

 undertaken in a similar manner to that of the English expedition, 

 the pans of water being boiled for a long time in vacuum, the 

 expelled gases being collected and afterwards analysed. The 

 result of these analyses pointed unmistakeably to a hitherto un- 

 recognised source of error, for the prevention of which a series 

 of supplementary experiments was necessary. The principal 

 results of these latter can be comprised under the following 

 heads : — 



1. The complete expulsion of the oxygen and nitrogen from 

 sea-water presents no difficulty ; it is accomplished as easily as 

 with fresh water. The proportion of oxygen to nitrogen is not 

 sensibly different in the first and last portions of the expelled 

 gas. 



2. The carbonic acid is only partially expelled by boiling the 

 sea-water for hours in vacuum ; the proportion of carbonic 

 acid found in the expelled gas justifies no conclusion as to the 

 amount in the water. It is, in the first place, dependent on the 

 length of time during which the ebullition has been continued ; 

 the portions of the sea-water gas first driven off is almost en- 

 tirely free from carbonic acid, the later portions are richer in it. 



3. The complete expulsion of the carbonic acid from the sei- 

 wa'er is attained by its distillation in a current of air free from 

 carbonic acid. Even under this operation, the carbonic acid is 

 detached so slowly, that only after the evaporation of a conside:- 

 able amount of water carbonate of lime begins to separate ; the 

 distillation must then be continued till, at the most, a fourth of 

 the original quantity of water remains. The carbonic acid 

 which is passed into baryta water can be conveniently estimated 

 by volumetric analysis. 



The fact that carbonic acid is present in large proportion in 

 sea water, not as a dissolved gas in the same sense as oxygen 

 or nitrogen, but in a peculiar condition of closer combination, 

 must be of great importance, not only as respects the animal and 

 vegetable life, but also the geological relations of the sea. 



I am now proposing to myself the problem to ascertain to 

 which constituent of sea-water is due its power of close combi- 

 nation with carbonic acid ; and to what extent the amount of 

 carbonic acid is proportional to its saltness. Full details will be 

 given in the Report of the German Baltic expedition. In the 

 expedition to be sent from here to the North Sea, application of 

 the experience hitherto obtained will be made to the estimation 

 of carbonic acid. 



Kiel, July 5 Oscar Jacobsen 



