404 



NATURE 



[July 24, 1919 



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 of Nature. No notice is 

 taken of anonymous communications.] 



Research and Service. 



There appeared in Nature for February 13 last 

 a criticism from the pen of Prof. F. Soddy of an 

 attitude expressed by me in my book entitled "The 

 Twin Ideals." As there seems to be some possibility 

 of misunderstanding, owing to the form of the work, 

 mav I briefly express the position I endeavoured to 

 indicate? Those who indulge in the monastic attitude, 

 who withdraw from the world and prosecute re- 

 search of a recondite character, are outside reasonable 

 criticism provided the work is done at their own 

 expense. If, however, this work is to be supported 

 from public funds, justification is necessary, and the 

 justification has appeared to me to be twofold. In 

 the first place, few people have the inclination or 

 capacitv for research, and it is therefore an attitude 

 that should be encouraged. In the second place, prac- 

 tical discoveries of value are at times made inci- 

 dentally to research of the kind. It appears to me, 

 however, that much damage is done by the assump- 

 tion on the part of such researchers that their efforts 

 are the only line of research worth considering. I 

 have never been able to satisfy myself that research 

 conducted with a definitely practical end in view 

 would not be equal to, if not more valuable than, the 

 monastic form. I have, therefore, simply asked that 

 in their attitude to the world at large those who prefer 

 the life of the scientific recluse should recognise the 

 equal value of the work of those whose inclinations 

 take them in a practical direction, and that they 

 should not seek to divert bright young intelligences 

 into their own channel of activities when they tend to 

 develop in the opposite direction. 



Furthermore, there seems to me to be a moral 

 obligation on all men of science to take practical steps 

 for the diffusion of the knowledge gained, so that 

 anything of practical value may be utilised by 

 humanity in general. It has seemed to me that the 

 monastic habit in researchers, together with indiffer- 

 ence to the immediate requirements of the world and 

 with the disposition to regard their own set of aptivi- 

 tieS as paramount, is apt to produce results that are 

 beneficial neither to the individuals concerned nor to 

 the nation. James W. Barrett. 



Sir James Barrett reiterates in his letter the views 

 he has expressed in his book "The Twin Ideals," 

 which I reviewed in Nature, but I fail to see how 

 they have been or can be misunderstood. He says 

 that at timqs practical discoveries of value are made 

 incidentally to researches pursued for their own sake, 

 apart froni practical ends, and that such investigators 

 assume their eflforts to be the only kind of research 

 worth considering. It would be more generally agreed, 

 I think, that all the great practical advances of the 

 present scientific era owe their origin to purely 

 theoretical investigations pursued for their own sake, 

 and that such work is as different from the pursuit 

 of practical discoveries of value as scientific explora- 

 tion is from prospecting for gold, minerals, or specific 

 commodities. To ask whether researches conducted 

 with a definite practical end are not equal, if not 

 superior, to those concerned with the advancement of 

 the boundaries of knowledge seems like asking 

 whether the fruit of a tree is not of equal or superior 

 value to its root. To suggest that those pursuing 

 NO. 2595, VOL. 103] 



researches of a recondite and academic character, who- 

 find it necessary for their work to withdraw largely 

 from the practical world of affairs and politics, are 

 only outside reasonable criticism if their work is 

 pursued at their own expense seems as unreasonable 

 as to deny nourishment to the roots of a tree because 

 of their recluseness, their indifference to the imme- 

 diate requirements of the world and inability to sur- 

 vive being hauled out into it. Frederick Soddy. 



Wild Birds and Distasteful insect Larvae. 



In the literature on mimicry and protective colour- 

 ing, many writers have claimed that both the larva 

 and imago of the currant moth {Abraxas grossu- 

 lariata, Steph.) are protected by colouring and an 

 acrid flavour, in consequence of which they are 

 usually rejected by wild birds. That the larvae of 

 certain. moths are distasteful to birds has been proved 

 by actual exi>eriment, but I have considerable doubts 

 as to the inclusion of the currant moth in this 

 category. 



In my work on the food of wild birds I have found 

 the imagines, and more often the larvae, of Abraxas 

 in the stomach of the song thrush, missel thrush, 

 blackbird, g^reat tit, whitethroat, house sparrow, 

 \ellow bunting, and cuckoo; and in 1918 large num- 

 bers of the larvae were found in the stomachs of the 

 song thrush and missel thrush over a period of sevea 

 consecutive days. 



In the case of the song thrush, the parent birds 

 were observed collecting these larvae during the first 

 five or six days after the young were hatched, and 

 were seen to bring the same to the nest, where they 

 were readily devoured by the young birds. Indeed, 

 a very large proportion of the food fed to the nestlings 

 during this period consisted of the larvae of Abraxas. 

 Then the parent birds suddenly ceased to feed uport 

 them. 



Knowing that the supply was by no means exhausted,, 

 the currant bushes were examined and numerous 

 larvae observed. Forty-one specimens were collected 

 and placed on fresh leaves in large glass dishes,, 

 but not one of the larvae reached the pupa stage. 

 From this collection we hatched out fourteen masses 

 of cocoons of Microgaster and twenty-seven specimens- 

 of Exorista. 



Although the currant bushes were very badly in- 

 fested with the larvae, we failed to find any pupae in 

 the soil beneath them, although it was collected and 

 most carefully searched ; moreover, during the present 

 season not a single larva of Abraxas has been found 

 on these bushes, and there must have been thousands 

 of them during 1918. 



Here, I think, we have an explanation of why the 

 thrushes ceased to feed upon the larvae, viz. because 

 they were parasitised, and also an excellent example 

 of two natural agencies — wild birds and insect para- 

 sites — practically exterminating what would un- 

 doubtedly have been a plague this year. 



It is v^ell known that the larvae of Abraxas are fre- 

 quentlv parasitised by the two above-mentioned in- 

 sects. ' Is it not possible that the parasitised larvae 

 alone are rejected by wild birds, and only the non- 

 parasitised specimens fed from ? 



Walter E. Collinge. 



The Universitv, St. Andrews. 



Science and Salaries. 



The issue of Nature for July 11 contains a large 

 number of advertisements of vacant posts of which 

 details as to salarv are stated in seventy-five cases. A 

 few advertisements, which have been omitted from 

 the following calculation, made no mention of salary. 



