3o6 



SCIENTIFIC NEWS. 



[Mar. 30, iS 



of ^aperis, 3lecture5, etc^ 



ROYAL INSTITUTION. 

 On March 15th the Rev. Dr. Dalhnger delivered his 

 second lecture on " Microscopical Work on the Least and 

 Simplest Forms of Life." 



He discussed in this lecture more closely the life- 

 history of the saprophytic microbia, taking up more 

 especially the species which appear on applying higher 

 temperatures to an apparently exhausted putrescent solu- 

 tion. In order to study their development under the 

 microscope, it was necessary to keep them at a tempera- 

 ture of about go° F., and to prevent the liquid in which 

 they live and move from drying up by means of an 

 atmosphere of steam. He first described the process of 

 fission, by which a great part of the multiplication of 

 these organisms, the one-seventy-five-thousand-billionth 

 of an inch in diameter, is effected. Each such ovoid body 

 becomes slightly elongated ; a depression is formed 

 about the middle, forming a kind of neck connecting two 

 bodies almost like a dumb-bell. This neck becomes 

 longer and thinner, and is finally ruptured, leaving two 

 ovoid. bodies like the original form of the parent. These 

 organisms rapidly grow, and then each undergoes fission 

 in the same manner. This process, however, reaches a 

 limit. A microbe in this state coalesces with another ; 

 they fuse into one, or rather the upper one is absorbed. 

 Shortly the cell opens and emits a cloud of minute germs, 

 each of which enters upon the same series of fissions as 

 the parent, whilst the membrane which enveloped them 

 sinks to the bottom. 



Prior to the introduction of the apochromatic lenses 

 the existence of nuclei in these micro-organisms was 

 known, but we were ignorant concerning their functions. 

 Now it is known that the nucleus is the governing power 

 of the entire cell, and that in it the processes of fission 

 and the development of the flagella take their origin. 



In these processes, which vary slightly in each species, 

 we find nothing but law and order. There is nothing of 

 the capricious or arbitrary, each of these tiny beings pre- 

 senting the record of numberless generations, and bearing 

 witness to the truth of the Darwinian principles of 

 " descent with variation " and of the survival of the 

 fittest. 



As already mentioned in our " Current Events" of last 

 week, the evening discourse, on March i6th, was given by 

 Mr. John Murray, of the Challenger expedition, on the 

 "Structure, Origin, and Distribution of Coral Reefs 

 and Islands." The aim of the discourse was to show 

 that since Mr. Darwin put forward his theory of the origin 

 of coral reefs and islands our knowledge has so grown 

 that it needs considerable modification, mainly with 

 regard to the point that the reefs do not necessarily 

 imply areas of depression. A long series of photographs 

 of coral-forming animals and of others co-existing with 

 them, of soundings, charts, and views was shown on the 

 screen, among them being a most interesting photograph 

 of the side of a reef taken by the Hon. Ralph Aber- 

 crombie just as a wave was receding. The picturesque 

 effect of coral reefs has often been described in poetic 

 language, but the lecturer thought the question how the 

 reefs were formed was not less interesting. The reefs, 

 we know, are composed mainly of carbonate of lime, and 

 some of the group of animals we call corals have the | 



power of secreting this from the sea water to form their 

 " skeletons." But the water has the power of dissolving 

 carbonate of lime, and so the existence of reefs would 

 seem to be the result of the balance between the selective 

 power of the corals and the solvent action of the sea. The 

 rate of solution, it is ascertained, varies with the tempera- 

 ture, but except for what may be called a film at the top, 

 sea water is nearly ice cold even at the Equator. It is 

 known that there are many more " cones " below the sea 

 surface than those which stand out above it as islands, 

 and telegraph ships have furnished records of 

 many which were unknown to the Challenger 

 staff. It is noticed that reefs exist in the warm 

 surface water areas. The windward side always gets the 

 richest supply of food, and here the coral growth is most 

 vigorous. The trustworthy data for estimating the rate 

 of deposit are but few, and it is doubtful at what depths 

 "building" commences; it may be 10 or 15 or possibly 

 50 fathoms. It is only round the edges of cones that 

 growth takes place, and the chances of a lagoon getting 

 filled up are small ; and when it is, it is generally with 

 blown sand. With regard to vegetation, it is curious to 

 notice that the trees grow right down to the water's edge, 

 though their roots are in salt water. The vegetation is 

 generally richest on the opposite side to that most 

 favourable for coral growth, and here under the trees it 

 is that the villages are found. Very few of the islands 

 rise much above sea level. Even the elevation of 

 Bermuda, which consists mostly of blown sand, is but 

 about 200 ft. Mixed with the carbonate of lime, the 

 result of coral growth itself, there is much that comes 

 from other sources, globigerina, radiolarians, etc., and 

 there is also a well-recognised pteropod ooze. Darwin's 

 experience was very limited in comparison with the 

 knowledge we now have, and it is not surprising that we 

 are able to correct some of his conjectures. 



PHOTOGRAPHIC CONFERENCE OF THE 

 CAMERA CLUB. 

 The second annual conference was opened on March 

 13th, in the theatre of the Society of Arts, and 

 continued on the following day. The meetings were 

 presided over by Captain W. de W. Abney, the Presi- 

 dent of the Club, and some very interesting papers were 

 read. Dr. D. G. Thompson in the first paper pointed 

 out the services photography was rendering in medicine 

 and the allied sciences. He mentioned that the vocal 

 cords had been photographed, as also had the interior of 

 the eye. Mr. H. Trueman Wood, M.A., in a paper on 

 the " Application of Photography to Scientific Purposes," 

 referred to its use in astronomy, meteorology, spectros- 

 copy, micrography, and geography. Mr. Traill Taylor 

 described a simple method of correcting single lenses 

 for architecture. Mr. G. S. Waterlow read a paper on 

 " Modern Photographic Engraving and Printing," which 

 we will shortly reproduce. Mr. G. Lindsay Johnson read 

 a communication on " Weights and Measures, and Ten 

 per Cent. Solutions," in which he suggested a new 

 system of weights, so as to avoid the confusion at present 

 existing between avoirdupois and apothecaries' weights. 

 Mr. W. Willis described in detail an " Improvement in 

 the Platinotype Process." A paper was read on the 

 " Present Value of Art in Photography," by Mr. J. F. 

 Mostyn Clarke, in vi/hich the author urged that more 

 attention should be devoted to artistic composition. 

 Captain Abney described the " Theoretical Aspect of 



