626 



NATURE 



[Oct. 24, 1889 



Prof. Weismann himself seems hardly to realize how 

 inevitable such a conclusion is. If it be admitted that 

 unicellular organisms acquire new characters under the 

 operation of external influences, it cannot consistently be 

 doubted that this also takes place in germ-cells. 



It seems to be necessary, therefore, to modify the 

 conception of variation founded upon the above-quoted 

 paragraph from p. 277, by introducing into it the opera- 

 tion of external influences upon the germ. We now see 

 that though sexual reproduction greatly promotes varia- 

 tion in consequence of the ever-new combination of an- 

 cestral characters in each fertilization, yet another efficient 

 cause of variation is the direct action of external influences 

 on the germ, giving rise to blastogenic characters. 



But this modified conception of the causes of variation 

 comes into collision with Prof. Weismann's statement 

 (p. 277) that " the origin of hereditary individual varia- 

 bility cannot indeed be found in the higher organisms — 

 the Metazoa and Metaphyta ; but it is to be sought for in 

 the lowest— the unicellular organisms," a collision which 

 is much to the detriment of the latter ; for, if it cannot be 

 denied that external influences give rise to blastogenic 

 characters, then it cannot be maintained that " the origin 

 of hereditary individual variability cannot be found in 

 the higher organisms." On the contrary, it must be 

 admitted that the modifying influence of external con- 

 ditions continually affects not only unicellular organisms, 

 but also the germ-cells of the Metazoa, producing new 

 characters, thus inducing variation, in both. 



This conclusion leads to the consideration of a point of 

 great interest. In accordance with his view of the pre- 

 eminent importance of amphigonic reproduction in caus- 

 ing variation, Prof. Weismann asserts the lack of varia- 

 bility in parthenogenetic forms, in the following words 

 (p. 290) :— 



' ' If my theory as to the causes of hereditary individual variability 

 be correct, it follows that all species with purely parthenogenetic 

 reproduction are sure to die out ; not, indeed, because of any 

 failure in meeting the existing conditions of life, but because 

 they are incapable of transforming themselves into new species, 

 or, infact, of adapting themselves to any new conditions. Such 

 species can no longer be subject to the process of natural selec- 

 tion, because, with the disappearance of sexual reproduction, 

 they have also lost the power of combining and increasing those 

 hereditary individual characters which they possess." 



The views contained in this paragraph appear to me 

 to be completely at variance with the facts known con- 

 cerning the Fungi, among plants. Thus, in the Sapro- 

 legniese, all the known forms, including several genera 

 and many species, are parthenogenetic ; the sexuahty of 

 the Ascomycetes is still the subject of discussion, but it is 

 admitted that many genera and species of these Fungi are 

 certainly asexual ; and the sexuality of the yEcidiomycetes 

 is extremely doubtful. These plants show no apparent 

 tendency to die out, in spite of the absence of sexuality. 

 But it may be replied that these families may be in the 

 stage in which sexuality is just disappearing, and in 

 which they are still adequately adapted to their condi- 

 tions of life. Such an objection cannot apply, however, 

 to the Basidiomycetes. These Fungi are not only entirely 

 asexual, but it would appear that they have been evolved 

 in a purely asexual manner from asexual ascomycetous or 

 .^cidiomycetous a ncestors. The Basidiomycetes, in fact, 

 afford an example of a vast family of plants, of the most 

 varied f"orm and habit, including hundreds of genera and 

 species, in which, so far as minute and long-continued 

 investigation has shown, there is not, and probably never 

 has been, any trace of a sexual process. How are we, 

 then, to account for all the variation which has taken 

 place in this group, quite independently of amphigonic 

 reproduction .'' On this point Prof. Weismann says 

 (p. 275) :— 



"If it could be shown that a purely parthenogenetic species 

 had become transformed into a new one, such an observation 



would prove the existence of some force of transformation othe'' 

 than selective processes, for the new species could not have been 

 produced by these latter." 



It appears to me beyond doubt that, in the Fungi, new 

 species have been developed from parthenogenetic forms, 

 but I leave it to Prof. Weismann to suggest what " force 

 of transformation other than selective processes" may 

 have been operative. 



It is not, however, argued that the variation of the higher 

 Fungi is as great as it might have been had they pos- 

 sessed sexuality ; for there can be no doubt that sexual 

 reproduction does very materially promote variation. It 

 seems probable, in fact, that the absence of sexuality in 

 these plants may be just the reason why no higher forms 

 have been evolved from them ; for in this respect they 

 present a striking contrast to the higher Algas in which 

 sexuality is well marked. 



Since it is clear that new hereditary characters can be 

 produced by the action of external influences on the germ, 

 the outcome of Prof. Weismann's investigation of the 

 phenomena of variation is that he has given prominence to 

 the fact that new hereditary characters need not be appa- 

 rent in the body of the parent, but that, on the contrary, 

 the somatogenic characters are just those which are least 

 likely to be transmitted. This is essentially the same 

 position, though stated in more precise terms, as that 

 taken up by Darwin, who held that it is not the sudden 

 variations, due to altered external conditions, which 

 become permanent, but those slowly produced by what he 

 termed the accumulative action of changed conditions of 

 life. 



With this I close my criticisms, not because there are 

 no other points which might be discussed, but because I 

 have already touched upon many of them in my " Lec- 

 tures on the Physiology of Plants" (Cambridge, 1886), 

 and because I desire at present to deal solely with the 

 more fundamental parts of the theory. I have, I think, 

 said enough to show that, interesting and suggestive as is 

 Prof. Weismann's theory of the continuity of the germ- 

 plasm, it by no means affords, at least in its present form, 

 so complete and ready an explanation of the facts of 

 embryogeny, heredity, and variation, as the enthusiasm 

 of some of his more ardent disciples would have us 

 believe. Sydney H. Vines. 



Oxford, September. 



NOTES. 



We regret to announce the death of Mr. John Ball, F.R.S., 

 which took place somewhat suddenly at midnight on Monday 

 last. We understand that the funeral will take place to-morrow 

 (Friday), at il a.m., at St. Thomas's, Walham Green. 



The Reports of the Eclipse Expedition of 1886 are at 

 length ready for publication, and will be issued immediately 

 as separate numbers of the Philosophical Transactions. The 

 first, " On the Total Solar Eclipse of August 29, 1886," is by 

 Captain Darwin, Dr. Schuster, and Mr. Maunder ; the second, 

 " On the Observations made at the Island of Carriacou," is by 

 the Rev. S. J. Perry ; the third, " On the Determination of the 

 Photometric Intensity of the Coronal Light," by Captain Abney 

 I and Prof. Thorpe ; and the fourth, " On the Observations made 

 at Grenville, in the Island of Grenada," by Mr. H. H. Turner. 



The collection of objects brought back by Prof. Haddon from 

 various islands in Torres Straits is now to be seen in a part of 

 the Eastern Assyrian room at the British Museum, on the upper 

 floor of the north-east angle of the building. Special interest 

 attaches to the anthropological specimens included in this valu- 

 able collection. 



The list of names to be recommended for the new Council of 

 the London Mathematical Society at its annual meeting, on 

 November 14, differs from that of last year in the following 



