Nov. 6, 1 8 73 J 



NA TURE 



19 



gramme at any part of the earth's surface, and the megadyne is 

 about I '02 times the weight of a kilogramme. 



The liilogram-metre is rather less than the erg-eight, being 

 about 98 million ergs. 



"■ The gramme-centimetre is rather less than the l<ilerg, being 

 about 9S0 ergs. 



For exact comparison, the value of g (tlie acceleration of a 

 body falling in vacuo) at the station considered, must of course 

 be known. In the above comparisons, it is taken as 980C.G. S. 

 units of acceleration. 



One horse-power is about three quarters of an erg-ten per 

 second. More nearly, it is 7 "46 erg-nines per second, and one 

 fo)xe Jc cheval is 7 '36 erg-nines per second. 



The mechanical equivalent of one gramme-degree (centigrade) 

 of heat is 41 '6 megalergs or 41,600,000 ergs. 



SCIENTIFIC SERIALS 



In the current number of the Quarterly yournal of Microscopic 

 Science, Mr. E. T. Newton commences with a paper on he 

 Structure of the Eye of the Lobster, his observation being the 

 result of suggestions from Prof Huxley. The structure of the 

 eye is minutely discussed, and the accompanying illustrations 

 are abundant. As a concluding remark, we read that "Notwith- 

 standing all that has been wnritten up to tlie present time con- 

 cerning the mode of action of the compound arthropod eye, we 

 are still unable satisfactorily to solve this difficult physiological 

 problem." — A paper by Prof. Betz, of Kieff, on the methods of 

 investigating the structure of the central nervous system in Man, 

 will be found of special interest, the hardening, cutting, and 

 tinting of specimens being discussed. — M. Pasteur's new con- 

 tributions to the theoi-y of Fermentation, are translated from the 

 " Comptes Rendus," and Prof. H. L. Smith's paper on Arche- 

 biosis and Heterogenesis, is reprinted from the Lens. — A 

 Resume, by Mr. W. Archer, of recent observations on Parasitic 

 Alga;, is followed by Dr. Klein's Contributions to the Anatomy 

 of Auerbach's Plexus in the Frog and Toad, and this by a 

 valuable series of observations by Prof Lister on the Natural 

 History of Bacteria, in which a study of the life of Bacteria 

 under different circumstances as regards the fluid in which they 

 grow, shows that their general appearance, size, and shape 

 depend in great measure on the fluid in which they are growing, 

 their removal from one to another fluid causing them to take on 

 quite a different form, and their replacement the reassumption of 

 the original condition. Many important facts are to be learned 

 from this paper. — Mr. E. R. Lankester describes in detail the 

 microscopic and spectroscopic appearances of a new Peach- 

 coloured Bacterium, named by him Bacterium rubescens. The 

 colouring matter he names Becterio-rubrin. This Bacterium does 

 not generally occur in isolated plastids, liut generally forming 

 films, encrustations, or tufts. Most are aggregated in adherent 

 masses, several excellent drawings of which accompany the 

 paper. 



The Journal of the Franklin Institute, Sept. 1873. — This 

 number contains a useful paper by Mr. Hugo Bilgram, on the 

 theory of steam governors. — In government reports on the 

 decay and preservation of timber, Generals Cram and Gillmore 

 recommend the Seely process as the best. It consists in sub- 

 jecting the wood to a temperature above the boiling point of 

 water, and below 300" Fahr. while immersed in a bath of creo- 

 sote a sufticient length of time to expel the moisture. When the 

 water is thus expelled the pores contain only steam ; the hot oil 

 is then quickly replaced by a bath of cold oil, by means of 

 which change the steam in the pores of the wood is condensed, 

 and a vacuum formed into which the oil is forced by atmospheric 

 pressure and capillary attraction. Gen. Gillmore thinks a 

 wooden platform, thoroughly creosotcJ, would last twenty to 

 thirty years, and be better than a stone pkatform during 

 that entire period. — An important paper by Prof. Thurston 

 (extracted from the /ran Age), treats of the molecular changes 

 produced in iron by variations of temperature. — Mr. Mott points 

 out the conditions of good construction in lightning rods, and Dr. 

 Feuchtwanger gives some information as to nickel and its uses 

 in the arts, coinage, and nickel plating. — An oil discovery of 

 unusually rich character is announced from the neighbourhood of 

 Titusville, Pa. ; the production of the new region being esti- 

 mated at 30,000 barrels per day. 



Der Naturforscher, September 1873. — We note, in this num- 



ber, two striking observations in animal physiology. One of 

 these refers to the torpedo, which has been a puzzle to physiolo- 

 gists, inasmuch as, while giving shocks strong enough to lame or 

 kill another animal, its own muscles do not show the least con- 

 traction. Du Bois Reymond's hypothesis is, that while the 

 stimulation to discharge goes forth from the central organ, the 

 same organ sends out at the same time a counteractive influence 

 through the nervous system, which neutralises the excitability of 

 the nerves. M. Franz Boll took a recent opportunity of ex- 

 perimenting with the fish on the Italian coast, and, among other 

 things, he tested this theory by cutting some nerves, and watch- 

 ing their muscles when he stimulated the electric nerves. The 

 neutralising stimulation being thus cut off, the muscles should, 

 he thought, contract, if the hyphothesis were true ; and they did 

 so, the muscles of the unsevered nei-ves remaining at rest. Still, 

 he hardly thinks the expermient decisive, because nerves are 

 more excitable after section. — The other observation is by Prof. 

 Fick, who has found, by manometric measurement, a less pres- 

 sure of blood in the left ventricle than in the aorta ; 80 mm. of 

 mercury in the one case, 104 to 12S in the other (in a dog). He 

 supposes the blood, only partially filling "the ventricle, at the apex, 

 to be shot against the semilunar valves, forcing them open by its 

 vis -c'iva. In the neighbourhood of the valves the pressure must 

 quickly rise. In short, as the author puts it, the lilood is not 

 pressed, but hurled [geschteuderl] into the aorta.— There is a use- 

 ful abstract of the chief points in a paper by Prof. Abbe (to 

 Schulze's Archiv) on the capabiUty of the microscope and its 

 limits. He seeks to show, by physical deductions, that the limit 

 of magnification is as good as reached, in our best systems. 

 Some curious observations by M. van Tieghem are given in a 

 note on tlie independence of the individual organs of the em- 

 bryo of plants. — M. Ebermayer, we find, has been examining 

 the influence of forests on ozone-contents of the air ; he st.ates 

 there is more ozone in and near forests than in the open, but 

 among the denser branches there is somewhat less than in the 

 open closely bordering the forest ; and in the tops of the trees 

 there is more than in the lower parts. — Several French Academy 

 notes are abstracted : on the magnetic force of anne.aled steel, 

 on development of electricity in liquid mixtures, on the planet 

 Mars, &c. ; also Royal Society papers. Some meteorological 

 observations as to distribution of heat in Switzerland deserve 

 notice. 



Bulletin Alensuel de la SociHf d' Acclimntation di Paris. 

 August. — In a paper on the "Causes of the Depopulation 

 of our Rivers," M. C. R. Wattel enters at length into the 

 question of the French river fisheries, which will be read with 

 interest by fish-culturists. Some interesting information as to 

 the effect of navigation and trade on the rivers is given ; but the 

 great danger to the fisheries lies in the unrestricted destruction 

 of immature breeding-fish : and M. Wattel recommends that 

 steps should be taken to prevent over-fishing and to facilitate 

 the erection of fishways on the rivers. — The notes of Dr. 

 P. Mares on the acclimatisation of various sorts of Eucalyptus 

 in Algeria, are interesting. — The results of the experiments 

 to produce different coloured silks go to show that silk- 

 worms fed on cherry-leaf produce a bright chromo-ycllow- 

 coloured silk, those on pear-leaves a darker shade of the same 

 colour, those on apple-leaves a nearly white silk, but coarser 

 than that of the silk-worms fed on mulberry-leaves. — An 

 extract is given of a work by M. E. Perns, on "Birds and 

 Insects," in which he considers the advisability of protecting 

 small birds. M. Ferris, granting all the birds are insecti- 

 vorous, either continually or occasionally, acknowledges the good 

 they may do, but doubts whether a large proportion of the insects 

 destroyed are hurtful to man ; and he raises the question whether, 

 therefore, it is desirable to protect birds to kUl what would other- 

 wise do no harm. 



The September number commences with a paper by the 

 Secretary on some Australian vegetables, the introduction of 

 which into Algeria is proposed. — An interesting paper on the 

 breeding of ostriches in captivity is contributed by Capt. Crepu, 

 who has kept several pairs of these birds. His observations 

 throw much light on the natural history of the ostrich. M. 

 Comber describes the mortality which has seized the deer and 

 other animals in King Victor l*~.mmanuel's park at La Mandria. 

 The calamity is at tributed partly to over-crowding and partly to 

 the want of shelter and proper protection. In 1S65, when the 

 park and grounds were carefully cultivated, 13 deaths occurred. 

 In 1873, the" park being left in its natural state, 172 deaths are 

 recorded. — An important paper on the production of milk is the 



