I 



ULY 



I, I 



NATURE 



335 



t of this scorpion, of which very elaborate details are given, 

 'vould appear not to agree closely with any other Arachnid type 

 yet described ; the development of the central and lateral 

 } es entirely confirms the descriptions of Lankester and Bourne, 

 as well as those of Parker, but Patten's conclusions are shown 

 to be without foundation. The mode of formation of the ventral 

 nervous system is exceptional among Invertebrates, resembling 

 rather that of Chordata. — On the morphology of the compound 

 eyes of Arthropods, by S. Watase (Plate xix.). Reprinted, 

 with a short introduction by the editor, from a recent number 

 of the " Studies from the Biological Laboratory, Johns Hopkins 

 University."— On the structure of a species of earthworm belong- 

 ing to the genus Diachseta, by Frank Beddard (Plate xx.). This 

 new species, D. 7vindlei, is from the Bermudas.— On HtkaUro- 

 hranclms shrubsoU, a new genus and species of the family 

 Spionidjc, by Florence Buchanan (Plates xxi. and xxii.). This 

 worm was found at Sheppey in soft mud, usually covered by an 

 inch or so of brackish water ; in addition to the figures of the 

 anatomical details there are coloured portraits of this Annelid. — 

 An attempt to classify earthworms, by Dr.W. B. Benham. Some 

 idea may be formed of the progress made within the last twenty 

 years in our knowledge of this group when we state that the 

 author enumerates and gives analyses of nine families of Lum- 

 bricomorpha, containing thirty-two genera and over 2Q0 species. 

 The author wishes the following correction made : —In Fig. 39, 

 which illustrates the anatomy of Lumbricus, the oesophageal 

 pouch (CP) is placed in somite xi. ; followed by a pair of calci- 

 ferous glands in the same somite and a second pair in somite xii. 

 The pouch (cp) should be in somite x. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, June 19.— "Contributions to the Molecular 

 Theory of Induced Magnetism." By J. A. Ewing, F.R.S., 

 Professor of Engineering in University College, Dundee. ' 



After referring to the discussion by Maxwell of Weber's 

 theory, which ascribes the magnetization of iron and other 

 magnetic metals to the turning towards one direction of molecules 

 which are already permanent magnets, and to suggestions by 

 Profs. Wiedemann and Hughes, and lately by Mr. A. E. 

 Kennelly (the Electrician, June 6 and 13, 1890), the writer 

 describes experiments which he has made bearing directly on 

 the molecular theory. The experiments have been made by 

 grouping near to one another a large nutober of small pivotted 

 magnets each free to turn about a fixed centre, and studying the 

 configuration which the group assumes and the manner in which 

 It yields when an external magnetic force is imposed. The 

 results do not support the idea that the molecular magnets form 

 closed chains in unmagnetized iron. They lead, however, to 

 the important conclusion that no arbitrary conditions of direc- 

 tional constraint need be postulated to make the behaviour of 

 the molecular magnets agree with what is known about magnetic 

 quality. ^ 



In the writer's view the molecular magnets are perfectly free 

 to turn in response to external magnetic forces, except in so far 

 as they are constrained by the magnetic forces which they 

 mutually exert on one another. This theory is briefly discussed 

 in the paper in relation to the form of the magnetization curve 

 to the character of cyclical processes, and to the known effects 

 of temperature, vibration, stress and so forth, and the following 

 conclusions are stated :— ... . *> 



( 1 ) That in considering the magnetization of iron and other 

 magnetic metals to be caused by the turning of permanent 

 molecular magnets, we may look simply to the magnetic forces 

 which the molecular magnets exert on one another as the cause 

 of their directional stability. There is no need to suppose the 

 existence of any quasi-elastic directing force or of any quasi- 

 fnctional resistance to rotation. 



(2) That the intermolecular magnetic forces are sufficient to 

 account for all the general characteristics of the process of mag- 

 netization, including the variations of susceptibility which occur 

 as the magnetizing force is increased. 



(3) That the intermolecular magnetic forces are equally com- 

 petent- to account for the known facts of retentiveness and 

 coercive force, and the characteristics of cyclic magnetic pro- 



; That magnetic hysteresis and the dissipation of energy 

 NO. 1083, VOL. 42] 



which hysteresis involves are due to molecular instability 

 resulting from intermolecular magnetic actions, and are not due 

 to anything in the nature of frictional resistance to the rotation 

 of the molecular magnets. 



(5) That this theory is wide enough to admit explanation of 

 the differences in magnetic quality which are shown by dif- 

 ferent substances, or by the same substance in different states. 



(6) That it accounts in a general way for the known effects 

 of vibration, of temperature and of stress, upon magnetic 

 quality. 



(7) That, in particular, it accounts for the known fact that 

 there is hysteresis in the relation of magnetism to stress. 



(8) That it further explains why there is, in magnetic metals, 

 hysteresis in physical quality generally with respect to stress, 

 apart from the existence of magnetization. 



(9) That, in consequence, any not very small cycle of stress^ 

 occurring in a magnetic metal involves dissipation of energy. 



Anthropological Institute, June 24.— E. W. Brabrook, 

 Vice-President, in the chair.— Mr. J. E. Price exhibited parts of 

 a skeleton found at West Thurrock, Essex.— Mr. H. H. Risley 

 read a paper on the study of ethnology in India. This paper 

 states the results of certain inquiries into the customs and 

 measurements of the features, stature, &c., of some of the chief 

 tribes and castes in India, conducted during the last five years 

 under the authority of the Government of Bengal. Owing to 

 the influence of the caste system, which forbids intermarriage 

 between members of different castes, India offers a peculiarly 

 favourable field for anthropological researches. The measurements- 

 disclose the existence of two extreme types— the Aryan and 

 Dravidian. The Aryan type— as represented by the Brahmans, 

 the Rajputs, and the Sikhs— is tall and fair, with a finely cut nose, 

 and features on the whole superior to those of the average 

 European. The Dravidians, as seen in the Kol tribes, who re- 

 cently revolted against the oppression of their Hindu landlords, 

 are short and very black, with a broad flat nose, closely ap- 

 proaching in its dimensions to that of the Negro. The proportions 

 of the nose are regarded by European anthropologists — by Prof. 

 Flower, F.R.S., of the British Museum, and Prof. Topinard, 

 of Paris— as the best test of race distinctions. The Indian 

 statistics bear out this opinion. They show that in Bengal caste 

 IS so closely connected with race that the social standing of a 

 caste is in inverse ratio to the average width of the noses of its 

 members. The lower the caste the broader and more Negro-like 

 is its nose; and conversely, in ascending the social scale, we meet 

 with continually finer noses, till in the higher castes European 

 proportions are reached. The proportions of the head are of 

 interest in connection with the theory propounded by Herr Karl 

 Penka, of Vienna, and favoured by Prof. Sayce, that the Aryans 

 were a dolichocephalic (long-headed) race who came originally 

 from Scandinavia. The long-headed type is very numerous in 

 the Punjab and North- West Provinces at the present day, and its 

 distribution is such as to give considerable support to Herr 

 Penka's opinions. The inquiry has also brought to light the 

 existence in Bengal of totems such as are found among the North 

 American Indians. Large tribes, like the Kols, are subdivided 

 into two or three hundred groups, each of which is called after 

 an animal, a tree, or a plant ; and the rule is that a member of 

 a particular animal group, such as the snakes, the tortoises, the 

 eels, or the mangooses, may not marry within that group. Thus 

 a snake man may not marry a snake woman, but must select his 

 bride from among the frogs, the tortoises, the mango-trees, or a 

 host of groups which include the whole fauna and flora of the 

 district. The paper attempts to account for this custom, which 

 the late Mr. J. F. McLennan called exojramy, by connecting it 

 with the theory of natural selection. Among other interesting 

 facts the Bengal inquiry shows that the practice of infant marriage, 

 and the custom forbidding widows to marry a second time, are 

 greatly on the increase, and are being adopted by the lower 

 castes as marks of social distinction. It is feared that the spread 

 of infant marriage will have a weakening effect on the race, and 

 will multiply and aggravate those special diseases of women 

 which Lady Dufi"erin's Fund was instituted to deal with. The 

 increase in the number of widows is in itself a great evil. It 

 lowers the position of women in India, and tends to lower the 

 standard of social morality. 



Paris. 

 Academy of Sciences, July 24.— M. Hermite in the chair. 

 --M. Boussmesq presented the second and last volume of his 

 ' Course of Infinitesimal Analysis," and commented upon the 



