344 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The so-called " horny fibres," which are better called " elastoidin 

 filaments," are intercellular products of mesenchyme cells. In the 

 fatty fin of the Salmonida3 the elastoidin filaments are well seen, and 

 here they are distinctly the product of mesenchyme cells. 



Heliotropism of Pelagic Animals.* — J. Loeb has experimented 

 with Copepods, larvae of Polygordms, and other plankton organisms in 

 order to get at a better understanding of the rising to the surface in 

 the evening and the descending movement in the morning. There is 

 a periodic change in the direction of the heliotropism : they are nega- 

 tively heliotropic in the morning, positive in the evening. Raising the 

 temperature makes them negative ; decrease of acids (especially C0 2 ) 

 in the water lessens the positive heliotropism ; very intense light 

 makes some organisms negative. There are other factors, such as the 

 friction of the water ; for (as Wolfgang Ostwald has pointed out) 

 this varies with the temperature, and for pelagic animals whose specific 

 gravity is greater than that of water it is easier to sink during the day 

 than at ni^ht. 



x &' 



Animal Life of San Bernardino Mountains.! — Joseph Griunell 

 gives an account of the " Biota " of the largest high mountain group in 

 southern California. He discusses the life zones as marked by fauna 

 and flora, and pays particular attention to the bird population and the 

 influences modifying it. He makes notes on 139 birds, 35 mammals, 

 and 20 species, not merely as to distribution, but as to habits as well. 



Cause of Appendicitis.^ — A. E. Shipley suggests, as others have 

 done, that Entozoa may play a part in the aetiology of appendicitis. 

 There is evidence that Oxyuris vermicularis sometimes perforates the 

 wall of the alimentary canal, and thus diffuses pathogenic bacteria. 

 Similarly Ascaris lumbricoides and Trichocephalus trichiurus may by 

 their punctures and perforations distribute bacteria which set up 

 inflammation. 



Are there Suprarenal Bodies in Invertebrates ? — H. Poll § discusses 

 this interesting question and the suggestions that have been made by 

 those who answer it in the affirmative. His own view is that certain 

 cells of the ventral ganglia of the leech are " chrome brown " ganglion- 

 cells and are analogous to suprarenal tissue. 



Tunicata. 



Constancy of Histological Elements in Oikopleura longicauda.[| 

 E. Martini means by this title that precisely similar cells are found in 

 precisely the same place in every specimen, and in similar relations to 

 their surroundings. He shows this to be the case to a very remarkable 



* Biol. Centralbl., xxviii. (1908) pp. 732-6. 



t Publications Univ. California, Zoology, v. (1908) pp. 1-170 (24 pis.). 



X Parasitology, i. (1908) pp. 263-79. 



§ SB. Ges. Nat. Freunde Berlin, 1908, No. 1, pp. 18-23 (1 pi.). 



|| Zeitschr. f. wiss. ZooL, xcii. (1909) pp. 563-626 (3 pis. and 22 figs.). 



