August 17, 1893] 



NA TURE 



369 



extrinsic and intrinsic-remain lilic, so long and no longer do 

 their effects remain constant. What effects a change in those 

 influences may produce experiment and observation, and these 

 alone can determine. 



For thousands of generations certain characters, such as 

 blindness and winglessness, and enormous size of head and of 

 jaws, and complete absence of all power of multiplication either 

 direct or indirect, either sexual or asexual, have rem lined con- 

 stant in "soldier" termites. No soldier termite has any 

 marked resemblance to any one of its ancestors. Yet each is 

 like every other "soldier," and that likeness is "heredity." 

 Its characters have not been " transmitted," for no ancestor 

 ever possessed ihem. Like conditions in successive gene- 

 rations lend to like results, one of which is the production 

 of a fairly constant proportion of neuter "soldiers" and 

 " workers " devoid of any power of reproduction. Those 

 " like conditions" include a constant, or nearly constant, struc- 

 ture of the males and females albeit the polymorphism extends 

 to these also. The recurrence of tho e like conditions has been 

 determined by natural selection, and is still maintained by 

 natural selection. To apply the term "transmission" in such 

 a case would be not more absurd than in any other case, sup- 

 posing the word to be ustd in its literal sense, for, though the 

 soldier in every case derives its characters from a line of ancestors 

 extending back to remote periods, not one ancestor in which 

 line has possessed those characters ; yet their geographical dis- 

 tribution at the present time shows that the characters of 

 ' ' soldiers " are of remote antiquity. This constancy of charac- 

 ters in many generations appears to be identical with the 

 phenomenon called "inheritance." 



Heredity then is a likeness of effects due to likeness in the 

 causes producing ihem. The likeness of causes has been pro- 

 duced and maintained by natural selection acting under fairly 

 constant conditions. "Inheritance" is a name given to the 

 operation of an influence which has no existence in nature. The 

 sooner we cease to use the word altogether the better it will be 

 for our science. 



" Inheritance of acquired characters " is a mere chain of words 

 correlated with a chain of loose ideas, but not correlated with 

 any natural objective phenomenon. To assert it as a fact is as 

 futile as to deny it. C. Herbert Hurst. 



0*ens College, Manchester, July 26. 



Echinocyamus Pusillus. 



May I direct your attention to a rather serious error contained 

 in the review of Theel's paper on Echinocyanius pusillus, which 

 appeared in your number (or August 3 ? 



Your reviewer states that "not the least brilliant and far- 

 reaching " of the advances in our knowledge of Echinoderm mor- 

 phology, made in the year 1891, is the discovery by Brooks and 

 Field of the primary bilateral symmetry " of the water- 

 vascular system " of Asterias. 



Had such a discovery been really made, it would no doubt 

 have justified the epithet applied to it by your reviewer ; but, 

 in the first place it was not made, and in the second Metschm- 

 koff long ago pointed out such a primary bilateral symmetry in 

 the embryos of Antphiiira squamata. 



Field's paper, containing the results of his own and Brooks's 

 work, appeared in the Quarterly yournal of Microscopical 

 Science {or 1892. In it he gives an account of the development 

 of the larva of Asterias ; but in the oldest stage which he 

 describes there is not as yet a trace of the water-vascular system. 

 He describes, it is true, in larvje of a certain size a right as well 

 as a left madreporic pore ; but as all " echinologists," it is to be 

 hoped, know by this time, the pore is primarily related to the 

 ca:lom, and only secondarily enters into connection with the 

 water-vascular system. Further, Field distinctly states that 

 ca-es of a double pore had been observed previously by conti- 

 nental zoologists, but regarded by them as pathological ; and 

 the chief point in Field's paper is the very probable theory put 

 forward by him that such cases constitute a distinct stage in the 

 ontogeny of the animal. E. W. MacBride. 



Z jological Laboratory, New Mu-eums, Cambridge, 

 August 5. 



On referring to my draft notes, which I happen to have kept, 

 I find in place of the words "water-vascular system," quoted 

 by your correspondent, " pore canal system " ; and I do not 

 deny that I should have done better had I transcribed them un- 



NO. 1242, VOL 48] 



changed. I fail at the same time to see that the "error" 

 complained of is, in its place, as serious as my critic would 

 imply. No one who attempts to do hi-; duty by the colossus of 

 biological literature would fail to be familiar either with the work 

 of the authors whom he cites, or with his own recent beginning 

 in a kindred direction. Admitting the claims of one and all, 

 the work of Field appeared to me to put the probability at 

 stake upon a much firmer basis than that of his predecessors, 

 and it was for that reason that I emphasised it. If I err not, a 

 journalistic notice is not a thing to be hampered with names 

 and details, especially when written with the dual object of 

 directing attention to a really admirable monograph, and of 

 endeavouring to promote an amicable spirit of brotherhood 

 among workers in science, such as we to-day very much 

 need. The Writer 01- the Notice. 



The Supposed Suicide of Rattlesnakes. 



The letter of Mr. Edward S. Holden on this subject is ex- 

 tremely interesting. It appears that he, like other individuals 

 who have imagined thU they have witnessed the suicide of scor- 

 pions, has fallen into the error (so com non in the interpretation 

 of biological as distinguished from abiological phenomena) of 

 stating his inferences and beliefs as though they were observa- 

 tions. The "instance which occurred before my eyes" (to 

 quote his words, which re nind one of the old herbalist, Gerard) 

 was simply that of a snake biting itself when imprisoned in a 

 jar of water. That the blow was " deliberate," "intentional," 

 and of "suicHal purpose" is pure speculation — and nothing 

 occurred before Mr. Holden's eyes to warrant his entertaining 

 such a notion. Had Mr. Holden been aware that the poison of 

 the rattlesnake has little or no effect upon another rattlesnake, 

 nor upon the individual from which the poison is furnished, he 

 would probably have been less ready to conclude that the bite 

 was one of suicidal purpose. He would then perhaps have 

 inquired as to the depth to which the bite penetrated into the 

 tissues of the snake, and how far such a superficial bite as a 

 snake can inflict upon a part of its own body is likely (in the 

 absence of any poisonous action) to be seriously injurious to the 

 snake. 



In this case, as in that of the scorpion confined in a fielry 

 circle (experimentally studied both by myself and by Prof. 

 Bourne, of Madras, and reported on in the Proceedings of 

 the Linnean Society and the Royal Society) the spasmodic 

 struggles of an animal artificially confined and tortured, have 

 been, as we clearly demonstrated, mistaken for efforts at self- 

 destruction. The biting of its own body by the snake may be 

 justly compared with the " biting the dust" attributed to men 

 who die in hand-to-hand struggle, or to the biting of their own 

 hand or arm by unhealthy children when sullering from a 

 paroxysm of anger. E. Ray Lankester. 



Oxford, August II. 



Imitation or "Instinct" by a Male Thrush? 



O.v the evening of July 19 a young thrush was caught in my 

 conservatory and placed in a large outside aviary. The follow- 

 ing morning I observed the parent birds feeding the young one 

 through the bars with worms. In the same aviary there had 

 been for more than ten years a male thrush which had been 

 captured when qviite young and had never been mated or 

 troubled v\ith family cares. On observing the parents of the 

 young bird feeding their offspring he at once followed their ex- 

 ample. On putting some bread and milk into the aviary he 

 flew down, took up a piece and tried to induce the young bird 

 to open its beak. At fir>t the young thrush appeared to be 

 afraid of accepting food from the foster-father, but after some 

 persuasion it allowed itself to be fed with bread and milk, hemp 

 seed, and other food. The parent birds were watching from 

 the outside, and during the whole time occupied by the old 

 male in feeding their progeny were also trying to introduce food 

 through the bars The day after (July 21) the parent birds did 

 not make any futther attempt to introduce food, but contented 

 themselves by watching their young one from a tree close at 

 band. If any of the house-cats approached the aviary the 

 parents would at once give the alarm. In the course of 

 another day or two they abandoned the young one entirely to 

 the care of the old foster-father, who has proved quite woithy 

 of his trust, as the young bird is now able to feed himself and 

 is in a very thriving condili jn. The old male still insists, how- 



