June 26, 1919] 



NATURE 



Z2>Z 



Miss Boring report the results of their study of the 

 corpus luteum in the hen. Its origin is from the 

 theca interna of the ovary, and it is clearly homologous 

 with the corpus luteum of the cow. The course of 

 its development is an abbreviation or fore-shortening 

 of that in the cow, corresponding, indeed, with the late 

 involution stages. Its resemblance to the corpus 

 luteum of the oviparous duckmole is striking. The 

 corpora lutea in hen and cow contain a similar yellow 

 fatty substance. In both there is a yellow amorphous 

 pigment in the cells containing the fatty substance. 

 In the hen a mass forms in an atretic or undischarged 

 follicle, which is practically identical with the 

 corpus luteum that forms in a discharged follicle. 



The same investigators have made a study of eight 

 cases of hermaphroditism in poultry (Journ. Exper. 

 Zool., vol. XXV., 1918, pp. 1-30, 9 plates, 9 figures). 

 The birds in question viere females with embryonic or 

 degenerating ovaries. Three were changing to a male 

 condition in respect to reproductive organs, external 

 characters, and even sex behaviour. But no struc- 

 tural counterpart was found for the abnormal 

 behaviour of one hen treading another hen. Develop- 

 ment of comb, spur, and wattles does not stand in 

 any direct quantitative relation to the sex-condition 

 of the gonad, but the shape and carriage of the body 

 have a general relation thereto. The amount of lutear 

 cells or pigment is in precise correlation with the 

 degree of external somatic femaleness exhibited by 

 the individual, but it does not appear that the inter- 

 stitial cells of the gonads have any causal relation to 

 the secondary sex-characters in the abnormal birds 

 here dealt with. 



We have not come to an end of the interesting 

 budget of papers from Maine. Thus there is an in- 

 vestigation by Prof. Pearl (Amer. Naturalist, vol. li., 

 1917, pp. 545-99 and pp. 636-39) redefining the con- 

 cept of inbreeding, and showing how the degree of 

 kinship between any two individuals may be most 

 precisely expressed. There is another by Prof. Pearl 

 and Mr. S. W. Patterson showing that milk production 

 changes with age in a definite manner (following a 

 logarithmic curve), and in Jersey cows reaches its 

 maximum at approximately the age of eight years 

 and seven months. J. A. T. 



SCIENCE AND INDUSTRIAL DEVELOP- 

 MENT. 



T^HE British Scientific Products Exhibition, which 

 -■■ has been organised by the British Science Guild, 

 and will be opened by the Marquess of Crewe at the 

 Central Hall, Westminster, on Thursday, July 3, will 

 afford an opportunity for vindicating the supremacy 

 of Great Britain in the field of discovery and inven- 

 tion. It will show the strength and variety of home 

 manufactures and indicate the indispensability of 

 science in industry, in peace as in war. 



One of the practical results of the exhibition should 

 be to create new markets for new products and estab- 

 lish new industries for dealing with raw materials. 

 The extent to which Germany had derived benefit 

 from the exploitation of these resources and in- 

 sidiouslv used her control to our disadvantage was 

 nut realised until after the outbreak of war. With 

 this knowledge before us, and the conviction that 

 most strenuous efforts will be made by Germany to 

 nppropriate trade and commerce which in Imperial 

 interests we should secure for ourselves, it is of the 

 utmost importance to accentuate the lesson which 

 events have taught us. The exhibition will provide 

 this means of enlightenment and its influence at the 

 present epoch cannot be over-estimated. 



We must leave for a later occasion the account of 



NO. 2591, VOL. 103] 



the main features of the exhibition, and direct atten- 

 tion here to the one aspect which deserves special 

 emphasis. Modern industry requires the use of a 

 greater number of skilled research workers and of 

 men with technical knowledge for responsible positions. 

 The census of production (1907) showed that the net 

 annual output per head is generally greatest in those 

 industries which employ the highest proportion of 

 persons receiving salaries as distinct from wages, and 

 it diminishes as one passes to industries where the 

 percentage of wage-earning employees increases. 

 Thus, taking the nine leading industries, but not 

 including coal-mining, the highest annual output per 

 head is 185/. in the chemical mdustries, where 12 per 

 j cent, of the persons employed receive salaries and 

 88 per cent, wages; next in order of annual output 

 per head and proportion of salaried employees come 

 iron and steel factories (ii8i.) and engineering fac- 

 tories, including electrical engineering (io8i.); and at 

 the bottom of the list are the jute, linen, and hemp fac- 

 tories with a net output of 61L only, the percentage 

 of wage-earners being 98, of salaried persons 2. 

 These figures indicate that the employment of skilled 

 technologists means increased productivity, and they 

 point to the importance of improved training of 

 artisans in technical schools. If research methods are 

 to be more generally applied to industries greater 

 skill and accuracy will he required from the general 

 body of workers, so that it is not merely the duty 

 of the universities and colleges to supply highly 

 trained research workers, but the technical schools 

 have also the important duty of educating the artisan 

 for the new type of work required under the new 

 conditions. 



The way to increase the number of highly skilled 

 technologists is to make their position and prospects 

 better than they have been. Many employers still 

 express their preference for the so-called practically 

 trained man over the man with scientific training, 

 whereas in other countries the college-trained techno- 

 logist finds ready acceptance in all branches of in- 

 dustry. Whether it is accepted or not, the fact 

 remains that much of the commerce and manufacture 

 of the modern world demands the leadership of highly 

 trained, widely informed men, and that these men 

 must be forthcoming if we are to be able to take a 

 leading place among the nations of the world. It 

 should be the purpose of an efficient educational 

 system to provide adequate opportunities forthe train- 

 ing of men of this type from whatever station of life 

 they may be selected. Of all methods of reconstruc- 

 tion none is more likely to add to national w^ealth 

 and strength than the application of science to in- 

 dustry ; and the more men there are capable of being 

 entrusted with it, the greater will be the progress. 



THE HISTORY OF THE LONDON PLANE. 



IN an article on "The Artificial Production of 

 Vigorous Trees," an abstract of which was pub- 

 lished in Nature, January 7, 1915, p. 521. Prof. 

 Augustine Henry directed attention to certam well- 

 known trees, like the Lucombe oak, Huntingdon elm, 

 cricket-bat willow, and black Italian poplar, which 

 owe their vigour and botanical characters to the fact 

 that thev are of hvbrid origin. Such hybrids arose as 

 chance seedlings due to cross-pollination of two trees 

 of different species growing together. The introduc- 

 tion into Europe during the seventeenth centurv of 

 North American trees which grew alongside similar, 

 but distinct, European species in parks and gardens 

 was the occasion of considerable hybridisation. Trees 

 like the black Italian poplar and the London plane, 

 which have never been seen anywhere in the wild 



