288 SUMMARY OF CURRENT RESEARCHES RELATING TO 



lation, often excessive, occurs in the liver cells immediately after re- 

 covery from psychic secretion : it is chiefly due to the presence of 

 glycogen in the cells ; the precipitate produced in the cytoplasm by 

 fixing reagents varies somewhat with the nature of the food ; changes 

 described as due to poisons are in some cases merely normal changes due 

 to functional activity. 



e. General. 



Photogenic Marine Animals.* — W. C. M'Intosh notes that since 

 he gave his British Association Address, sixteen years ago, on the phos- 

 phorescence of- marine animals, noteworthy progress has been made only 

 in two departments — (1) as regards the role of photogenic bacteria, and 

 {2) in the extension of our knowledge of luminous fishes. 



As a general rule, phosphorescence in marine animals shows itself 

 under four conditions, three of which are connected with structure : — 



1. The animals present special cells which, under certain circum- 

 stances, secrete a phosphorescent mucus. 



2. The special cells produce light without mucus or other visible 

 secretion. 



3. The animals emit light under the action of the nervous system 

 without special differentiation of the tissues. 



4. The phosphorescence is due to photogenic bacteria. 



The author in his luminous lecture gives a wealth of examples of 

 these various kinds of " phosphorescence." 



Pelagic Animals. - ! - — C. Apstein has written a little book for travellers 

 giving an account of the open-sea animals and their distribution, dealing 

 also with the colour of the sea, phosphorescence, and the like. 



Genesis of Protoplasmic Motion and Excitation .} — T. Brailsford 

 Eobertson sketches a theory. Loeb and others have shown that proteids 

 take up ions to form a loose compound (ion-proteid), These ion-proteid 

 molecules must always be breaking down, and there must be a number 

 of free ions in any protoplasmic body, and therefore a difference of 

 potential between it and its medium. 



If changes in surface tension take place, movements must follow, 

 but since the number of free ions in a protoplasmic body must always 

 be changing, or subject to change* the surface tension must also change. 



This mode of accounting for movements is used to interpret gal- 

 vanotaxis, chemotaxis, muscle-contraction, plant movements, etc. " It is 

 probably capable of explaining the whole of the vast complex of facts 

 which have been gathered together under the head of phenomena of con- 

 tractility and irritability." 



Activity of the Isolated Heart.§ — M. Lambert finds that by using 

 Ringer's fluid the excised heart of the frog may be readily kept spon- 

 taneously beating for five days. The chief cause of arrest in such cases 



* Zoologist, x. (1906) pp. 1-20. 



t Das Tierleben der Hochsee. Kiel (1905) 115 pp., 174 figs. See also Zool. 

 Zentralbl.. xiii. (1906) pp. 160-1. 



X Trans. Roy. Soc. S. Australia, xxix. (1905) pp. 1-56. 

 § Comptes Rendus, cxlii. (1906) pp. 597-9. 



