330 SUMMARY OF CURRENT RESEARCHES RELATING TO 



nucleus itself increases sometimes to double the original diameter. In 

 the larger atrichous forms, division may take place, both of nucleus and 

 cytoplasm. Buds may be given off without nuclei, but they appear to dis- 

 integrate and die. As a rule, the chromatin of the nucleate forms is cast 

 out into the cytoplasm, and later to the outside, when the organism 

 dies. The author discusses the " extraordinary parallel " which exists in 

 the changes he describes and certain so-called "sexual" processes in 

 Protozoa. 



Light-reactions in Volvox.* — S. 0. Mast describes in detail the 

 reactions of V. globator and V. minor to light. The eye-spots are situated 

 on the outer posterior surface of the individuals. Volvox rarely moves 

 exactly in the direction of the light-rays, but deflects, apparently under the 

 influence of gravity, up or down or to the side, the degree of deflection 

 being least for strongly positive colonies exposed to light of optimum 

 intensity. The motion is regulated by the relative intensity of the light 

 on opposite sides of the colony. Orientation is not the result of "trial 

 and error," but is brought about by motor reactions in the individuals 

 composing the colony. Volvox is positive in comparatively low, and 

 negative in comparatively high light-intensities, but there is great varia- 

 tion in regard to this, depending upon the physiological state of the 

 colonies. Weber's law seems to hold for the light-reactions of Volvox. 



Trypanosome of the Eel.f — C. Franca gives an account of Trypano- 

 soma granulosum Laveran and Mesnil, which is very abundant in 

 Anguilla vulgaris in Portugal. The species has very distinctive nuclear 

 characters, and it occurs in two well-marked varieties, parva and magna. 

 Culture in the blood of the eel gives rise to " herpetomonad " forms. 

 No endocellular stages are found in the eel's blood. 



New Piroplasma from a Rodent.} — C. Nicolle describes a new 

 Pwoplasma from Ctenodactylus gondi Pallas, an Octodont of North Africa. 

 It appears to be common ; it resembles the Leishman body in appearance, 

 and has the peculiarity of dividing into four, not two, daughter-cells. 

 The author names it Piroplasma quadrigeminum. 



Structure and Life-history of Copromonas.§ — C. C. Dobell gives an 

 account of Copromonas subtilis from the rectum of Rana temporaria, and 

 discusses various points in flagellate morphology. There is an asexual 

 and a sexual cycle in the life-history. During the former, multiplica- 

 tion takes place by longitudinal division. After a time the monads 

 conjugate in pairs, and reducing divisions of the nuclei take place, 

 followed by encystation. The cysts are capable of being dried up. 

 These are swallowed by frogs and toads, and reach the rectum by way of 

 the digestive tract. As a rule the cysts do not liberate their contents 

 (a small hyaline monad) until the fseces have left the frog, but some- 

 times the monads emerge from their cysts and lead a semi-parasitic life 

 in the large intestine. Development does not appear ever to be com- 

 pleted inside the frog. 



* Journ. Comp. Neurol, and Psych., xvii. (1907) pp. 99-180 (15 figs.). 



t Bull. Soc. Portugaise Sci. Nat., i. (1907) pp. 94-102 (1 pi.). 



t C.R Soc. Biol. Paris, lxiii. (1907) pp. 213-16 (1 fig.). 



§ Quart. Journ. Micr. Sci., lii. (1908) pp. 75-120 (2 pis. and 3 figs.). 



