2IO 



NATURE 



[December 14, 191 1 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part o/ NATURE. 

 No notice is taken of anonymous communications.] 



The Relation of Big Game to Sleeping Sickness. 



The article by Sir Harry Johnston in Nature of 

 December 7 on " The Preservation of the African Fauna 

 and its Relation to Tropical Diseases '* j^ives a most 

 admirable and sympathetic review of the subject ; but there 

 is one statement to which I must venture to take excep- 

 tion as not conveying, in my opinion, an accurate 

 impression of the known facts of the case, namely, the 

 following sentence : — *' But within the last twelve months 

 or so it has been proved conclusively by the biologists at 

 work in Uganda that the large antelopes of that country 

 are the hosts of dangerous trypanosomes, amongst others 

 of the trypanosome which causes sleeping sickness." 



So far as I am aware, this statement is based on the 

 experiments reported by Bruce, Hamerton, and Bateman 

 (Proc. Roy. Soc, B, 83, pp. 311-27), in which it was 

 shown " that antelopes can be readily infected with sleep- 

 ing sickness by the bites of artificially infected tsetse- 

 flies " (p. 317), and that "the flies (Glossina palpalis) 

 when infected by the virus of sleeping sickness obtained 

 from the blood of infected antelopes are capable of trans- 

 mitting the virus to susceptible animals " (p. 319). These 

 results are based entirely on experiments conducted in the 

 laboratory, and the authors state expressly that " positive 

 evidence " is required " to complete the chain of evidence 

 that antelope living in the fly-areas may act as a reservoir 

 of the virus of sleeping sickness. So far it has only been 

 proved that they are ' potential ' hosts " (p. 325; the italics 

 are mine). 



The only instances known to me in which Trypanosoma 

 gambiense, the trypanosome of sleeping sickness, has been 

 identified as occurring in the blood of wild animals, natur- 

 ally infected, are two in number, and in each case the 

 animal was a monkey, and the locality Uganda ; one such 

 case is reported by Koch, Beck andKleine {Arbeiten k. 

 Gesundheitsamte, xxxi., p. 18); the second is reported by 

 Bruce and his collaborators (Sleeping Sickness Reports, 

 xi., p. 102). If there are other known instances of T. 

 gambiense occurring naturally in wild animals, 1 should 

 be glad to be informed of them ; if there are not, however, 

 it seems to me premature to state that antelopes have been 

 proved to be the hosts of the trypanosome of sleeping 

 sickness. If laboratory experiments have shown them to 

 be the potential hosts of T. gambiense, the same can be 

 said of many other animals which can be inoculated with 

 this trypanosome in the laboratory. The following list of 

 animals susceptible to T. gambiense is taken from Laveran 

 and Mesnil, " Trypanosomes and Trypanosomiases." p. ",Sj 

 (translated by Nabarro ; Baillidre, Tindall ami lux. 

 1907) : — monkey (several species), lemur, dog, jackal, cat, 

 rabbit, guinea-pig, rat, mouse, jerboa, hedgehog, marmot, 

 "Ofse, donkey, cow, goat, and sheep. This list is based 

 chiefly on experiments performed in Europe, using 

 European mammals or exotic animals in captivity, and 

 there is no doubt it could be greatlv extended by anvone 

 experimenting systematically in the tropics on tropical 

 animals; but as it stands it is sufl^cientlv extensive, and 

 indicates that a great many species of wild animals, small 

 or large, might be incriminated as potential hosts of 

 i. gambiense equally with the antelopes, and that the 

 destruction of the " big game " alone would be likelv to 

 produce very little amelioration, if any, in the conditions. 



the whole history of sleeping sickness in Uganda indi- 

 cates that the disease has been imported from the west 

 by human agency (compare Laveran and Mesnil, op. cit., 

 PP- 359-«6), and that man is the primarv host of the 

 tr.vpanosome, at least in Uganda. If, however, the para- 

 site has now been transmitted from man to other suscep- 

 tible animals by the tsetse-flies, there is no reason to 

 repard the antelopes or other big game as having 

 monopolised the functions of being " reservoir " hosts of 

 the virus. From the point of view of preventing the 

 NO. 2198, VOL. 88] 



infection from ipreoding from animak to man, drnnett 

 animals would seem to be a much greater danger as 

 resTvoir of the virus than antelopes and creatures t) 

 n:it nets of which impel them to keep at a distaii' 



fn lints of human beings. 



li, ill' ( i-iiirc, it ■ •' — ■ ' • ...:-.-...- .1- ... .1 1-- 



of T. gambiense 



it would not Ixr su „ „ , ., 



be necessary to convert the whole country into an w 

 inhabited and lifeless desert. In my humble opinion t) 

 method of preventing the spread of sleeping sickn> " 

 futile one, and not likely to yield us<iful results. I 

 that there is only one practicable method of " -i J 



the transmission of the trypanosome, and v I 



measures calculated to destroy or keep down - ' 



flies. At the present time the most urgent n' 

 knowledge of the bionomics of the species < 

 and of their natural enemies. Some years ago 1 niadt: ili« J 

 suggestion in Nature (November 8, 1906) that fowls, wiUt a 

 or domesticated, would be likely to be efficient in k 

 down the flies by scratching up their pupae and 

 them, but, so far as I am aware, no experiment ...■.- 

 ever been carried out to put this notion to the test. So fl 

 long as sleeping sickness cannot be made amenable to M 

 treatment, attention must be concentrated on prevention, m 

 the central problem of which, in my opinion, is the destruc- * 

 tion of the insects concerned in the transmission of th- 

 disease. E. A. Minchin. 



Lister Institute of Preventive Medif'- ' *- ' 

 Gardens, S.W., December 9. 



The Inheritance of Mental Characters. 



The reply of Dr. C. Walker to Dr. Archdall K 

 your issue of last week seems to me somewhat qui 

 and suggests rhat he is not intimately acquainted ... 

 Prof. Pearson's Huxley lecture. The particular part < 

 this lecture quoted by Dr. Reid, and referred to by Di 

 Walker, reads actually as follows, the italics being Prot 

 Pearson's own: — " . . . We have found the same degr< 

 of resemblance between physical and psychical character-. 

 That sameness surely involves something additional. // 

 involves a like heritage from parents. The degree <' 

 resemblance between children and parents for the physic; 

 characters in man may be applied to the degr» ■ 

 resemblance between children and parents for ps 

 characters. We inherit our parents' tempers, our p. 

 conscientiousness " (not consciousness, as printed in D: 

 Reid's quotation), "shyness, and ability, even as W' 

 inherit their stature, fore-arm, and span." 



Now surely Dr. Walker cannot justly charge Dr. Re; 

 with misinterpreting Prof. Pearson's statement in th 

 instance, where Dr. Reid apparently infers from the woni- 

 " a like heritage " that Prof. Pearson meant " inherited n 

 the same way"; and that the words "a like heritage' 

 implicitly connote in this context an actual identity of th 

 modes of transmission and reproduction of a p.' 

 " conscientiousness " with those of the transmis-.iu 

 reproduction of a parent's fore-arm. Nor, it seems, 

 it be unfair to impute, on this ground, to Prof. ?• 

 the doctrine that external influences brought to bear > 

 child, such as experience of the world, training, ex 

 &c., could not have any greater effect on his ul. 

 " conscientiousness " than any external influences con 10 

 exert on the ultimate length of his fore-arm. 



London, December 10. H. Brv.w P-^vLtv 



I THINK Dr. Walker is scarcely clear as to the mh 

 A personal acquaintance with a writer is not ne( 

 when we judge his published opinions. By " char.i 

 biologists mean any trait of a living being — a head, n 

 a characteristic of a hair, a characteristic of that chai. 

 istic, and so on. Of course, no character of any sort- 

 neither a head nor a scar, for example — can develop in th- 

 individual unless the potentialit>' to develop it undo- '"' 

 conditions is antecedently present. If. then, we thi 

 terms of germinal potentiality, all characters, for es 

 heads and scars, are equally inheritable. But bic 



commonly apply the term " acquired " to actual 



characters which have developed under the influence 

 use or injury, the term " inborn " to characters whic 



