360 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Dimorphism and Fusion in Fusulinids.* — Hans v. Staff discusses 

 the pronounced dimorphism in Fusulina and other forms, regarding the 

 macrosphseric generation as probably asexual, and the microsphasric as 

 sexual. He also discusses the fusion of very young stages in Fusulinids. 



Intracellular Agglutination in Pelomyxa.f — A. Stole gives reasons 

 for believing that Pelomyxa produces intracellular agglutinins and lysins, 

 and that the same is true of amoebae and other Protozoa. Like the 

 making of ferments, so the making of agglutinins and lysins is a funda- 

 mental property of the cell. 



Amoeba of Dysentery in Cochin-China.j — F. Noc finds that there 

 is an amoeba commonly associated with abscess of the liver and dysen- 

 teric ulcers. It is also found in the drinking-water and in vegetables 

 gathered from the surface of the ground. It bears some resemblance 

 morphologically to Entanucba histolytica. 



Habits of Didinium nasutum.§ — S. 0. Mast describes the reactions 

 of this Ciliate protozoon, with special reference to the feeding habits, 

 and the functions of the trichocysts. The organism is approximately 

 ellipsoidal in form, slightly flattened at the anterior end. From this 

 end there arises an apparently fibrous conical projection, at the apex of 

 which the mouth is situated. The protuberance contains numerous 

 rod-like structures, and the whole forms a "seizing organ." When 

 Didinium comes in contact with an organism it usually responds with 

 the avoiding reaction, always turning towards the same side, in spite 

 of the fact that it is radially symmetrical. It feeds entirely on living 

 organisms, principally Paramacium. It captures these organisms by 

 coming in contact with them in swimming about at random. The 

 prey is held by means of the seizing organ, which in some way adheres 

 to the surface with which it comes in contact. 



There are no trichocysts discharged from the Didinium : these come 

 from the victims. The seizing organ is not thrust out at the victim, 

 nor is the prey paralysed by poison injected through this organ. The 

 trichocysts function as organs of defence. They are discharged in 

 great numbers when the seizing organ fastens itself to the ectosarc. 

 This forces the aggressor back mechanically, and frequently breaks the 

 connection, so that the victim regains its freedom. 



Well fed specimens of D. nasidum continue to divide for some time 

 without food, becoming smaller and smaller until they are not more 

 than one-tenth of the original size. Encysted forms are frequently 

 found. The chemical composition of the solution in which they live 

 seems to cause them to encyst, rather than lack of food, as maintained 

 by Thon. The apparent choice of food is due to the fact that the 

 seizing organ will adhere to the surface of some organisms and not of 

 others. The Infusorians come in contact with all sorts of objects in 

 their random swimming, and attempt to swallow all those to which the 

 seizing-organ will adhere. 



* SB. Ges. Nat. Freunde Berlin, 1908, pp. 217-37 (13 figs.). 

 t SB. k. Bohm. Ges. Wiss., 1908, No. 5, pp. 1-5. 

 % Ann. Inst. Pasteur, xxiii. (1909) pp. 177-204 (4 pis.). 

 § Biol. Bull., xvi. (1909) pp. 99-118 (18 figs.). 



