620 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



Protozoa. 



New Tentaculate Amoeba.* — B. Collin describes a remarkable form, 

 Chlamijdamorha tentaculifera g. et sp. n., which has a gelatinous shell 

 readily def ormable, and tentacles like those of Suctoria. It was obtained 

 from a marine culture of sand and seaweed collected at Thau. The 

 tentacles probably illustrate convergence ; in its nucleus and pseudopodia 

 the creature is clearly an Amoeba. Perhaps it may be placed near 

 Trichosphserium, between the Thecamcebge and the (jrymnamceba3. It 

 occurred in large numbers along with Amcebte, Foraminifera, a species 

 of TrkJiosphserinm, and the remarkable reticulate Rhizopod with a very 

 large nucleus, Rhizoplasma venrorni, the last named being previously 

 known only from the Red Sea. 



Reproduction of Paramoscium.f — L. L. Woodruff finds that if the 

 environment is favourable Faramcecium goes on dividing indefinitely. 

 Conjugation is not necessary for the continuance of life. The constant 

 environment of l)eef extract solution proved entirely wholesome. There 

 was no deterioration. 



There are normal minor rhythms in the rate of reproduction which 

 are due to unknown intracellular phenomena. The temperature co- 

 efficient of the average rate of multiplication is approximately 2 • 70, and 

 the rate is influenced by temperature at a velocity similar to that for a 

 chemical reaction. There is a marked parallelism between the order of 

 the toxicity of many cations toward Parmnoicium and the ionic potentials 

 of the ions. Subjection to small amounts of alcohol increases the 

 susceptibility of the organisms to copper sulphate. Excretion products 

 of Parammcium have a decidedly depressing effect on its rate of repro- 

 duction. 



Five-year Pedigreed Race of Paramoecium without Conjugation. % 

 L. L. Woodruff started a culture on May 1, 11)07, with a "wild" 

 Parammcium aurelia, which was isolated from an aquarium. Its four 

 first descendants were isolated to form four lines. The pedigreed culture 

 has been maintained by a specimen isolated from each of these lines 

 practically every day, thus precluding the possibility of conjugation 

 occurring, and facilitating a record of the number of generations 

 attained. During the five years there have been 3029 generations. The 

 mean rate of division is over three divisions in forty-eight hours. The 

 organisms of the last generation are as healthy as those of the first. This 

 seems to show that the protoplasm of a single cell may be self-sufficient 

 to reproduce itself indefinitely, under favourable environmental condi- 

 tions, without recourse to conjugation, and indicates that senescence and 

 the need for fertilization are not primary attributes of living matter. 



Conditions of Conjugation in Stylonichia.§ — G. A. Baitsell has 

 experimented with Stylonlchia pustulata in different culture media. A 

 culture in beef-extract medium died out at the 403rd generation, fol- 



* Arch. Zool. Exper., x. (1912) Notes et Revue No. 4, pp. Ixxxvlii.-scv. (2 figs.). 



t Biochem. Bull., i. (1912) pp. 396-412 (1 pi.). 



X Proc. Soc. Exper. Biol., ix. (1912) pp. 121-3. 



§ Jouru. Exper. Zool., xiii. (1912) pp. 47-75 (1 pL). 



