174 SUMMARY OF CURRENT RESEARCHES RELATING TO 



stances (reserves, pigments, free secretions, fixed secretions, intra-cellular 

 and extra-cellular skeletal structures, and other accessory structures 

 formed by excretion, and cell-fluids if not included in the following 

 groups — (C) the " rheoplasms " (like hsemolymph, blood-plasm, etc.), 

 and (D) excretions and nutritive particles within or outside the proto- 

 plasm. 



Then there are the substances which compose protoplasm : — (1) 

 karyoplasm (including karyohyaloplasm and karyomorphoplasm) ; (2) 

 cytoplasm (including hyaloplasm and morphoplasm — Leydig's spongio- 

 plasra) ; (3) paraplasm (including " organoids," mitochondria, chondrio- 

 konts, etc.). 



Thirdly, there are formed elements (cells, syncytia, fibrils, etc.), 

 which may occur in masses (plasmodia, matrix, lamelhie, etc.). Fourtlily, 

 there are layers in elements and masses, e.g. endoplasm and exoplasm. 

 Fifthly, there are fibrils, fibres, lamellse, and rods, wdiich may be classified 

 according to function, origin, relations, and composition. 



The author goes on to further groupings — (6) as to degrees of 

 vitality ; (7) as to inorganic, "anorganoid," and organoid materials of 

 construction ; and (8) as to the plasmic and metaplasmic nature of the 

 constructive substances. 



c. Greneral. 



Life in the Sea.* — James Johnstone has written an admirable in- 

 troduction to the study of marine biology, especially as regards the larger 

 problems of the economy of the sea. After referring to the transforma- 

 tion of marine biology by the methods of quantitative estimation of the 

 plankton and by the investigation of the influence of currents and other 

 physical conditions on the floating or swimming population, the author 

 discusses the various zones and areas of marine life, the rhythmic changes 

 in the sea, the factors determining distribution, the modes of nutrition, 

 and the sources of food. The discussion of these themes incorporates 

 much recent research and personal experience, and is marked by vigour 

 and lucidity. We may direct attention to the sketch of life at great 

 depths ; to the discussion of external periodicities in their relation to in- 

 ternal rhythms; to the contrast drawn between life in warm and life in 

 cold seas ; to the judicious treatment of the role of tropisms ; and to the 

 careful exposition of the hypothesis that a saprozoic mode of nutrition is 

 very general among the lower marine organisms. The book is particu- 

 larly valuable as a well-thought-out personal presentation of a subject, 

 the literature of which is voluminous, scattered, and in some respects 

 difficult without a guide. 



Progression in the Mammal. f—T. Graham Brown finds that the 

 rhythmic sequence of the act of progression is determined by phasic 

 changes innate in the local centres, and that these phases are not essen- 

 tially caused by peripheral stimuli. The proprio-receptive stimuli, which 

 are generated by the contraction of muscles taking part in the act of 



* Life in the Sea. By James Johnstone. Cambridge University Press (1911) 

 150 pp. (illustrated). 



t Proc. Eoy. Soc, Series B, Ixxxiv. (1911) pp. 308-19. 



