174 



NATURE 



[Dec. 26, 1878 



tain chain. To every observer, indeed, this must be obvious. 

 Two reasons have been adduced in explanation — i. That the 

 glaciers have been smaller from the cold of the glacial period 

 not having extended over Italy, as indicated by the absence of 

 the reindeer and other sub-arctic species from the drift ; 2. That 

 denudation has been enormous. In spite of the southern ex- 

 posure it hardly appears probable that there could have been 

 sufficient difference in the size of the northern and southern 

 glaciers to cause this contrast, as long as the glacial period 

 lasted, for the vapour-laden winds from the sea must have de- 

 posited much of their moisture on the southern slopes as snow. 

 But, as the ice-age passed away, the southern aspect of the Alps 

 would doubtless be freed from its influence sooner than the 

 northern, and hence, while snow and ice reigned in the latter 

 area, the regions south of the mountains underwent denudation, 

 probably, for a vast period. I would therefore suggest that the 

 comparatively small amount of glacial d^dris on the southern side 

 of the Alps may arise from that region having been exposed for 

 a much longrer time to sub-aerial waste, and in particular to the 

 floods caused by the more rapid melting of the snows on the 

 southern slopes of the mountains. Geo. A. Gibson 



10, Old Square, Birmingham, December 16 



Electric Lighting 



In the Proceedings of the Philosophical Society of Manchester 

 Mr. Wilde has described a new electric lamp, in which the 

 carbons are placed parallel to each other, as in a Jablochkoff 

 candle, but without any insulating material. It may not be 

 apparent to all why the arc always locates itself at the extre- 

 mity of the pair of carbons, and this, as Mr. Wilde observes, 

 whether the lamp be erect or inverted. The explanation is that 

 the current in each carbon repels the electric arc exactly as the 

 current in the mercury-troughs repels the connecting cross-wire 

 in a well-known experiment of Ampere. In Wilde's candle we 

 have two fixed conductors, the carbons, and a movable con- 

 ductor, the arc. Since the current in the arc and the current in 

 either carbon are one from the other towards the point of 

 junction of that carbon with the arc, the arc must be repelled by 

 the carbon. One cannot but be surprised that Ampere's ex- 

 periment did not suggest the discovery made by Mr. Wilde, 

 that the insulating material might with advantage be omitted in 

 Jablochkoff 's candle. J. HOPKINSON 



4, Westminster Chambers, December 12 



The Reproduction of the Eel 



The time of spawning and the differences between the sexes 

 of the common eel has been hitherto unknown. Last year for 

 the first time in this country eels {Attguilla bostoniensis) contain- 

 JJig eggs were found, December 31, by Mr. Edwards, at New 

 Bedford, Mass., as stated by Mr. Putnam in the Proceedings of 

 the Boston Society of Natural History. From observations on 

 eels brought me at Providence, R.I. it appears that eels spawn 

 here in salt or brackish water from October to the end of 

 November, as I have found several eels containing eggs which 

 seemed nearly ripe, the ovary being full and large. To-day on 

 examining the testis of a male eel 17 inches long, the mother- 

 cells and sperm-cells were found, the latter numerous and lively, 

 from gp^oo to irjmn) i^^ch in diameter. The eggs were white, just 

 large enough to be distinguished by the naked eye, measuring a 

 little less than \ mm. in diameter. The females are larger than 

 the males, with the belly white, while the males are easily dis- 

 tinguishable by the dark bellies and a narrow silvery or golden 

 median stripe. A. S. Packard, Jun. 



Laboratory of Brown University, U.S., November 27 



AERA TED BREAD 



COME remarks upon aerated bread which were made 

 ^-^ by Dr. B. W. Richardson at the recent general 

 meeting of the company working Dr. Dauglish's patents 

 require examination. Now it is noteworthy how im- 

 perfect oiu- knowledge of the chemistry of the mill- 

 products from the cereal grains still remains. Without 

 such knowledge we are not in a position to dogmatise as 

 to the exact nutritive values of different kinds of bread. 

 As I pointed out in a previous article on " Real Brown 



Bread," ' the statement that whole wheaten meal, bran, 

 pollard, &c., contain more nitrogen, and therefore more 

 flesh-formers than fine flour, rests upon no certain basis 

 of analytical fact. And if it were proved that all the 

 nitrogen of the most nitrogenous of mill-products does 

 really exist in what are called albuminoids or flesh- 

 formers, we cannot ignore the presence of much in- 

 digestible fibrous material in bran and pollard, material 

 which is not only non-nutritive itself, but which locks up 

 in an inaccessible form much of the real nutrient sub- 

 stances associated with it. Thus a sample of wheaten 

 bran, or rather, fine pollard, may refuse to give up to the 

 boiling dilute acid and alkali used in fibre-determinations 

 more than six-sevenths of its nitrogenous matter ; and 

 it can hardly be expected that the secretions of the ali- 

 mentary canal will prove successful in withdrawing a 

 larger proportion. Indeed, the analysis of the residues 

 of such foods after having been submitted to the digestive 

 process, has confirmed this expectation in the case of the 

 human subject. Moreover, while a not inconsiderable 

 part of the albuminoid matters of the outer coverings of 

 the grain thus escapes digestion from its mechanical con- 

 dition, there is good reason to believe that a further 

 portion remains unabsorbed, by reason of the rather 

 hurried passage of the branny particles through the 

 digestive tract. And the same causes which operate to 

 prevent a part of such flesh-formers as exist in the bran 

 from being utilised, affect also and in a similar way the 

 useful mineral substances which abound in the coarser 

 mill-products, as well as the oil or fat which they contain. 

 Now let us see what are the distinctive advantages 

 claimed for Dr. Dauglish's bread-making process by Dr. 

 Richardson. It yields a bread which is said to be " per- 

 fectly clean, perfectly wholesome, and completely nutri- 

 tious." As to the perfect cleanliness of this mechanical 

 process for making bread there can be no question ; it is 

 immeasurably superior to the barbarous and old, but, as 

 Dr. Richardson remarked, not "time-honoured system 

 of kneading dough by the hands and feet of the work- 

 man." And we may agree, with almost equal confidence, 

 in the statement that aerated bread is perfectly whole- 

 some. The stream of pure water charged with carbonic 

 acid gas vesiculates the dough, which has required 

 neither alum, nor blue vitriol, nor lime-water, to check 

 the irregular fermentation, and neutralise the sourness of 

 mouldy or otherwise damaged or inferior flour. But, on 

 the other hand, the adoption of the aerating process does 

 not of itself necessarily exclude all adulterations of the 

 bread : materials to whiten the loaf and to cause the 

 retention of a larger percentage of water may still be 

 used. As to the small loss of nutrient materials involved 

 in the ordinary fermentation of dough, it hardly merits 

 consideration. Perhaps Dr. Richardson alluded to it 

 because it gave him an opportunity of having a fling at 

 his old enemy, alcohol, of which it has been found that 

 a newly-baked loaf, made by means of yeast, contains 

 about o'25 per cent. So that a man who eats twenty 

 quartern loaves has therein consumed an amount of 

 alcohol which is commonly contained in one bottle of 

 port ! But if there be no really serious loss of starch 

 by conversion, first into sugar, and then into carbonic 

 acid gas and alcohol, there can be no doubt that a 

 number of altered products are present in a fermented 

 loaf, and that these are less abundant and less variable 

 in nature in aerated bread. But the presence in fermented 

 bread of larger quantities of sugar, gum, and soluble 

 starch than are found in aerated bread is not usually a 

 disadvantage so far as the digestibility of the loaf is con- 

 cerned. It is rather to the production of lactic acid and 

 of nitrogenous ferments by the use of yeast or leaven that 

 we should attribute the uncertain value of ordinary bread. 

 The quality of the yeast, too, must not be left out of con- 

 sideration, as some of our home and of our imported 

 supplies are by no means of a satisfactory character. 



' See Nature, vol. xviii, p 28g. 



