586 



NATURE 



[February 2q. iqi 2 



The enormous distinction between animals and plants 

 retjardinn the problems under discussion is brouj^ht about 

 primarily by the fact that in plants ihe asrxiinl ^iticralion 

 has underj^one increased evolution, in animals the sexual 

 generation. 1 might, indeed, have cited the peach tree, 

 cjuoted by Prof. Dendy, instead of the chrysanthemum. 

 Peach trees, as anyone who tends a garden knows, are 

 reproduced asexually by grafts, and not sexually from seed, 

 as Prof. Dendy assumes. 'Ihe reason is simply that peach 

 trees do not " come true " from seed. Probably the ever- 

 green condition would not be repeated from seed. Coming 

 true in grafts, this is a good example of my contentions. 



A true theory of heredity, like the mnemic one, must be 

 founded in a correct embryology, and this theory of 

 Hering's is the sole one which can be shown to conform 

 with the facts of the cycle of animal life. All other theories 

 known to me are based in direct development — an impossi- 

 bility. In developmental researches, which extend back 

 so far as 1888, antithetic alternation of generations has 

 proved itself to be the only possible mode of animal 

 development. Moreover, this is in accord with Pasteur's 

 fundamental researches establishing the stereochemistry of 

 niiturally occurring organic compounds. Those who with 

 Weismann and Haeckel hold to direct development, or any 

 theories of heredity based on this, live in a universe in 

 which there is no science of stereochemistry, and in which 

 the naturally occurring organic compounds have no action 

 upon the plane of polarised light. 



Nor do identical twins arise as Weismann supposed. 

 The whole " evolution theory " of \\'eismann is full of 

 such baseless hypotheses. If ordinary identical twins (AB, 

 .\B) arise so, how do the rarer ones (.AB, BA), where the 

 one is the looking-glass image of the other, externally 

 and internally, come about ? Or how are identical triplets 

 produced, or the seven to twelve identical embryos from a 

 single egg in the seven-banded armadillo, Prao/)MS /lybriVitis? 

 Embryo or sexual generation does not, as is so generally 

 believed, ever arise by the first few divisions of the egg. 

 The facts and reasons contained in this and my former 

 letter — though they do not profess to be all the pertinent 

 facts — may serve to indicate why a correct appreciation of 

 the cycle of animal life is so important for all theories of 

 heredity, and, one might also add, for all theories of the 

 origin and nature of cancer. For under current false 

 theories of development cancer is "an incurable disease," 

 whereas in the light of a true embryology and in that of 

 stereochemistry it is a natural phenomenon, which Nature 

 has demolished for untold millions of years, and which man 

 also can cope with and destroy whenever he sees fit to 

 imitate her and to use her methods. J. Bearo. 



8 Barnton Terrace, Edinburgh, February 15. 



(1) I QUiTK agree with Dr. Reid that the mnemic hypo- 

 thesis does not demonstrate the transmission of acquire- 

 ments. What I said in my review was that the mnemic 

 theory is based upon a belief in the inheritance of acquired 

 characters — a statement that anyone may verify who will 

 take the trouble to read Prof. Semon's book. I should 

 perhaps have qualified the statement by saying " Prof. 

 Semon's Mnemic Theory," though personally I cannot 

 conceive of a mnemic theory which is not so based. 



The inheritance or non-inheritance of acquired characters 

 is, of course, still an open question, but it is interesting 

 to^ reflect that such inheritance was assumed as a matter 

 of course by the great founders of the theory of organic 

 evolution — BufTon, Erasmus Darwin, Laniarck, and 

 Charles Darwin — and was never called in question until 

 the latter part of the nineteenth century. Before that time 

 no one thought it necessary to make experiments to prove 

 or disprove what everybody believed ; since then there has 

 not been time to make anything like enough experiments, 

 but some of those which have been made certainly seem 

 to indicate the possibility of the inheritance of acquired 

 characters in the strictest sense of the term. It is not a 

 question which can be answered dogmatically or by any 

 amount of a priori argument. It was just as reasonable 

 for Lamarck and others to suppose that such characters 

 can be inherited as it is for Weismann and his followers 

 to suppose that they cannot. Let us wait and see what 

 the future may bring forth. 



NO. 2209, VOL. 88] 



(2) If Dr. Beard will read the review whmh ^avf m < .isk 

 for his first letter, he will find it plainly stated that tii- 

 peach trees in Bordage's experiments were raised from 

 seeds. Had they been raised in the ordinary way fron. 

 grafts there would, of course, have been no point in tli 

 observations, and 1 certainly should not have thought :' 

 worth while to direct attention to them. 



I suppose all upholders of the mnemic theory will agr> 

 that if th<.' germ-(ells could not rememlx-r events in tli' 

 past history of the race, no developmental unfolding wou! i 

 be possible. 'Jhe important point seems to be that tl 

 events in question have, for the most part at any rat. 

 been experienced by the body and not by the germ-cell- 

 and that unless the germ-cells received information of th> i 

 from the body they could not remember them at all. Tli 

 view necessarily assumes that the body is able to transm 

 impressions to the germ-cells, which, as I said before, i 

 the fundamental idea of the doctrine of the inheritance < 

 acquired characters. The experiences of the body are suj 

 posed to depend, in the first instance at any rate, upon tl 

 environment, and to give rise to " acquired " character- 

 and such characters, according to the mnemic theory, i: 

 fluence the germ-cells and are transmitted by them to tl 

 bodies of future generations. 



I do not propose to discuss Dr. Beard's views < 

 animal development, but I think it ought to be clear 1 

 stated that the mnemic theory, as ordinarily understood, 

 is entirely independent of any such views. If Dr. Bear I 

 has a mnemic theory of his own that is another matter, 

 but it might be well to call it by some other name. 



Arthur Dendy. 



How Pollen is Collected by the Hoaey-bee. 



On February ii, a mild and sunny day, my bees wer 

 working busily on Eranthis hiemalis, the winter aconit' . 

 and by watching them I was able to verify my opinion, 

 published in The British Bee Journal of December 14, 1911. 

 that the pollen is collected by being scraped into the fissiii 

 between the tibia and metatarsus, and is compressed ai 

 forced out into the " corbicula," or pollen-basket, on t! 

 outside of the tibia by the closing of the fissure, a cor 

 elusion suggested by the examination of the hind leg of 1 

 queen humble-bee. 



One bee was watched for more than five minutes riflinj^ 

 flower after flower. During this time the load of poll' n 

 in each corbicula increased in size considerably, but th»' 

 bee did not once cross its legs and scrape the pollen-lad< n 

 metatarsal brushes on the upper edges of the opposit-' 

 tibi;e, which was the way that Cheshire supposed t! 

 corbicula was loaded (" Bees and Bee-keeping," vol. 

 p. 132). On the other hand, the inner sides of the mei 

 tarsi were frequently rubbed together, the motion ben . 

 longitudinal, and it was evidently by this rubbing ■ 

 scraping that the corbiculaj were loaded, for the hind i' u 

 did not come into contact with one another in any oth^ 

 way. 



Several other bees were watched, and were found i'- 

 behave in exactly the same manner. In all cases the poll- '^ 

 was gathered on to the metatarsal brushes direct from tl 

 j'nthers as the result of the bee crawling about amongst ih 

 stamens. 



My observations were hampered by a gusty wind, which 

 disconcerted the bees, and they were soon brought to 

 close by the sunshine passing off the flowers, so that sever 

 points that I had hoped to clear up still remain obscure. 



One of these is the way in which the pollen dust 

 moistened with nectar. The only satisfactory manner 

 which, it seems to me, this can be done is for the tongi 

 to lick the tarsi or metatarsi of the fore legs, which .'. 

 covered with stiff bristles well suited for holding the nect.r 

 the nectar being then transferred to the metatarsal brush- 

 on the middle legs, and from these, again, to the met 

 tarsal brushes on the hind legs. The latter being th 

 rendered sticky, the pollen dust would cling to them. Tl 

 different pairs of legs were certainly brought togeth 

 occasionally, but not after every scrape of the hind met. 

 tarsi, and their movements were so quick that it w, - 

 impossible to see what was done. Still, several poller 

 collecting bees that I killed had the tarsi and metatarsi > 

 the fore legs and the metatarsal brushes of the middle ai 

 hind legs moistened with nectar, and I think it probab: 



