ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 391 



activities by means of artificial imitations of protoplasm. A drop of 

 clove oil in a mixture of three parts of glycerin and one part of 96 p.c. 

 alcohol will behave like an amoeba, putting out pseudopodial processes, 

 creeping about, and even dividing. More than this, by adding a drop of 

 alcohol to the drop it is possible to cause it to move in a definite direc- 

 tion — towards the side at which the alcohol was introduced, and by 

 heating areas of the medium, it is possible to make the artificial amoeba 

 react to the stimulus of heat as a living one does. Again, if an artificial 

 amoeba be made with a drop of chloroform floating on water, it is pos- 

 sible to imitate the apparent choice of food-substances which is so 

 striking a feature of the living organism. In brief, the chloroform drop 

 is attracted to and flows round such substances as it is able to dissolve, 

 just as an amoeba flows round particles it is able to digest ; both amceba 

 and chloroform drop are repelled from substances they cannot dissolve. 

 Very striking is an experiment whereby a chloroform drop is seen to 

 fold up and enclose a thin thread of shellac, many times longer than the 

 diameter of the drop, just as an amoeba folds up and encloses a long 

 thread of an alga. Again, drops of chloroform can be made to build up 

 shells from fine particles of glass, entirely analogous to the shells 

 formed naturally by Difflugia. The author gives such details as to 

 render possible the repetition of his experiments. 



Radiolarians of Faroe Channel and Shetlands.* — Dr. R. N. Wolf- 

 enden has made some interesting discoveries in his plankton investiga- 

 tions round the Shetlands and in the # Faroe Channel. A new species of 

 Collozoum (C. brandtii) occurred in great swarms; Thalassiosolen atlan- 

 ticus is a new genus and species ; the singular Challengerida were not un- 

 common, e.g. Challengeron walwini sp. n. and Challengeria zetlandica sp. n. 



Changes in the Geotaxis of Paramcecium aurelia.f — J. Sosnowski 

 points out that this infusorian usually exhibits negative geotaxis ; it 

 swims to the top of an upright tube. But in some cultures, after the 

 shaking involved in transferring the individuals to the upright tube, 

 there is in some cases a very marked temporary positive geotropism, for 

 the individuals swim to the foot of the tube. A rise of temperature, 

 in some cases to 24° C, in other cases to 37° C, was found to have a 

 similar effect in changing negative to positive geotaxis. The investigator 

 notes that chemical changes in the medium have a similar influence. 



Reactions of Infusorians to Carbonic and other Acids.J — H. S. 

 Jennings and E. M. Moore show by very careful experiments : (1) that 

 .some infusorians, e.g. Colpidium colpoda, Gyclidium glaucoma, and Chilo- 

 monas paramcecium, collect in solutions of carbonic and other acids, just 

 as Paramcecium does, so that the spontaneous collections of these or- 

 ganisms may be due to their excretion of carbon dioxide ; (2) that others, 

 Loxocephalus granulosus and Oxytricha aeruginosa, form spontaneous col- 

 lections similar to those of Paramcecium, but do not gather in carbonic 

 or other acids, so that their aggregations must be due to other causes ; 

 (3) that many, e.g. Oxytricha fallax, Euplotes cliar on, Stylome.tr a pustulata, 



* Joum. Mar. Biol. Ass., vi. (1902) pp. 344-61 (2 pis. and 1 chart). 

 t Verh. Akad. Wiss. Krakaw, xxxviii. See liot. Centralbl., lxxxviii. (1901) 

 pp. 199-200. % Amer. Joum. Physiol., vi. (1902) pp. 233-50 (6 figs.).! 



