516 



SCIENCE. 



[Vol. VIII., No. 20O 



be looked for, and which therefore may be omitted 

 so as to place the key in the most faverable light, 

 there remain 229, which lead to families, genera, and 

 groups of species. Now, what characters are em- 

 ployed in these higher categories ? Will it be 

 believed that there are only about one-fourth of them 

 which have the slightest allusion to a single struc- 

 tural feature ? That seventy-two per cent are alto- 

 gether given up to the mere matter of the coloring 

 of the wings, rarely including even the distribution 

 of this color in patterns ? This is the key which ' A. 

 Reader ' pronounces ' excellent ; ' which subserves 

 no possible use as a guide to relative structure or 

 affinities, but only to discover a name. Its author 

 and ' A. Reader ' a^Dpear to be afflicted with the same 

 malady. Your reviewer surely made a mistake in 

 calling the key ' fairly good,' for it teaches nothing 

 of the basis of affinities, which it might have been 

 made to do without lessening one whit its value in 

 the special direction sought. 



Samuel H. Scuddee. 

 Cambridge, Nov. 26. 



Abnormal embryos of trout and salmon. 



In Science observer, vol. v. No. 1, pp. 1-8, S. 

 Garman and S. F. Denton have figured and described 

 a number of abnormal embryos of trout and salmon ; 

 and, under the head of ' Conclusions,' offered " a 

 few conjectures as to the cause and manner of origin 

 of these monstrosities." These conjectures appear 

 to merit a word of comment. Considering it im- 

 probable that many of the forms described could 

 arise by fission, an attempt is made to account for 

 their origin at separate points of the surface of the 

 vitellus. It is argued that several spermatozoa must 

 penetrate the egg-membrane at different points. But 

 how can they accomplish this when only one place 



— the micropyle — has been provided for their 

 entrance ? The possibility — not to say probability 



— of all passing through the micropyle does not 

 appear as one of the conjectures. ' Plurality of 

 micropyles ' is noted as one of the possibilities, but 

 another hypothesis is urged as the more acceptable ; 

 namely, imperfections in the egg-membrane, due to 

 premature extrusion of the eggs. " The finishing 

 touches being put on the outer covering of the egg, 

 the capsule is most likely to prove unfinished if the 

 eggs are taken too soon. . . . While the capsule 

 in maturity may resist the intrusion of sjoermatozoa, 

 compelling entrance at the micropyle, in imperfect 

 condition the same capsule would prove a less effective 

 barrier at its pores or elsewhere." All this seems to 

 be disposed of by the well-known fact that the mem- 

 brane is formed long before the egg is rijDe enough 

 to develop. It has been shown that the micropyle 

 is only large enough to admit one spermatozoon at a 

 time, and the impossibility of entering the minute 

 pores has been pointed out more than once. 



A strange assumption underlies most of these con- 

 jectures : it is the idea that a spermatozoon, without 

 uniting with the female pronucleus, can give rise to 

 an embryo. This point is not directly asserted, but 

 taken for granted, as if it had nothing unnatural or 

 preposterous in it. In the light of what is now 

 known of fecundation, such an idea, to say the least, 

 is wholly untenable. But if this idea is drojaped, 

 most of the ' conclusions ' are left completely in the 

 air. 



That superfetation may be the cause, or one of the 



causes, which leads to the formation of monsters, 

 has been made very probable by recent observations ; 

 but we can hardly regard this as a certainty so long 

 as such men as Professor Kupffer maintain that more 

 than one spermatozoon is required for the normal 

 fertilization of these very fish-eggs. 



As to the mode of origin of monsters, — if I may 

 be allowed to express an opinion on the merits of 

 the various theories that have been offered on the 

 subject, — I should say that LerebouUet and Rauber 

 are the only ones who have succeeded in presenting 

 views which are acceptable from an embryological 

 stand-point. Rauber has dealt with the subject in 

 a very thorough manner, and has shown how two or 

 more embryos could arise from the same germ-ring. 

 If two embryos were formed at opposite sides of the 

 ring, their final position would be on opposite sides- 

 of the egg, with the heads pointing in the same 

 direction, precisely as represented in the figures of 

 Garman and Denton. We can hardly do better than 

 accept this view until something better is offered to 

 replace it. In supposing themselves limited to the 

 alternatives of, 1°, fission, and, 2°, formation at dif- 

 ferent germinal centres, these authors have entirely 

 overlooked the more rational mode of interpretation 

 suggested by LerebouUet (Ann. des sc. nat., 1863), 

 and amplified and extended by Professor Rauber 

 (Virchow's Arch. f. pathol. anat. Ixxi. No. 1, and 

 ' Primitivstreifen und neurula der wirbelthiere,' 

 Leipzig, 1877). C. O. Whitman. 



Milwaukee, Nov. 25. 



The deepest fresh»water lake in America. 



Mr. L. W. Bailey's letter with the above heading 

 {Science, Yiii p. 412), calling attention to the extraor- 

 dinary depth of Crater Lake in Oregon, seems to 

 indicate that he regards Lake Temisconata, in the 

 Province of Quebec in Canada, as being an excep- 

 tionally deep fresh-water lake. The subjoined figures 

 will illustrate to what extent this idea is sustained by 

 actual soundings : — 



There seem to be unaccountable discrepancies in 

 the deptbs assigned by different authorities to the 

 chain of lakes lying between Canada and the United 

 States. The table of mean deptbs given in John- 

 ston's ' Physical atlas ' and in Herschel's ' Physical 

 geography ' must be erroneous. Some authorities 

 give the maximum depth of Huron as about 1,800 

 feet. The depth of Lake Baikal appears to be 

 almost incredible {vide Nature, xvii. p. 468). 



John LeConte. 



Berkeley, Cal., Nov. 17. 



