182 SUMMARY OF CURRENT RESEARCHES RELATING TO 



connection of the phenomena of life for the real ground in thought of 

 purposive adaptation. 



Introduction to the Study of Organic Evolution.* — Prof. D. Ker- 

 foot Shute has written an introduction to this study, primarily intended 

 for medical students, but sure to be useful in a much wider circle. He 

 hits the mean between over-simplicity and unnecessary technicality, and 

 is clear and interesting in his treatment of protoplasm and the cell, 

 maturation and fertilisation, segmentation and development, heredity 

 and variation, natural selection and isolation, and so on. 



The Story of Life's Mechanism.!— In this little book Mr. H. W. 

 Conn gives a useful epitome, in popular language, of the phenomena 

 connected with the living body of both animals and plants : — the 

 structure of the cell and of protoplasm, the phenomena of growth and 

 of reproduction, and other allied subjects. The illustrations are 

 numerous and clear, though often too diagrammatic. 



Normal Presence of Arsenic in Thyroid.J — Prof. A. Gautier has 

 demonstrated the presence of minute quantities of arsenic in the normal 

 thyroid glands of man, dog, pig, sheep, &c. Apart from insensible quan- 

 tities in the skin, arsenic is absent from the organs of the body except 

 thyroid, thymus, and brain. In the thyroid it exists in combination with 

 nucleins (arsenonucleines), along with the usual phosphoric nucleins. 

 It is well known that arsenical medicines have been used with advantage 

 in treating diseases of the thyroid, which adds to the interest of Gautier 's 

 discovery. No health apart from the thyroid may be translated no health 

 without arsenic. 



Reducing and Oxidising Diastases in the Animal Organism. § — 

 J. Abelous and E. Gerard conclude that in aqueous macerations of the 

 horse's kidney there is a coexistence of a soluble reducing ferment and 

 a soluble oxidising ferment, the presence of the latter perhaps causing 

 the disappearance of a certain proportion of the products due to the 

 former. 



Origin of Paired Limbs of Vertebrates. || — Mr. J. Graham Kerr 

 discusses critically the two hypotheses which have been proposed to 

 account for the origin of the paired limbs of Vertebrates, — the view that 

 the limbs are the persisting and exaggerated portions of a once continu- 

 ous lateral fin-fold, and the view that the skeleton of the paired limbs 

 and their girdles is derived by modification from a series of gill-rays 

 attached to a branchial arch. He gives his reasons for regarding these 

 suggestive speculations as unsatistactory, and propounds a hypothesis 

 of his own, that limbs may have been evolved from external gills. These 

 arise (in Urodela) from knob-like outgrowths from the outer face of 

 branchial arches, covered with ectoderm and possessing a mesoblastic 

 core ; the "balancers" seem to be serially homologous with them; they 

 crop up in the Crossopterygii, the Dipnoi, and the Urodela, i.e. in three 

 of the most archaic groups of Gnathostomes ; they are provided with ele- 

 vators, depressors, and adductors, and are thus potentially motor organs. 



* 'A First Book in Organic Evolution,' London, 1899, 8vo, xvi. and 2S5 pp., 

 12 pis. (10 coloured), and 27 figs. t London, 1S99, 218 pp., 50 figs. 



I Comptes Rendus, cxxix. (1899) pp. 929-36. § Tom. cit., pp. 1023-5. 



H Proc. Cambridge Phil. Soc, x. (1899) pp. 227-35. 



