ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 425 



families are recognised : — Pantostomatinese, Protomastigineaa, Disto- 

 matinef©, Chrysomonadinese, Cryptoinonadinese, Chloroinonadineae, and 

 Euglenineae. 



New Genus of Peridiniese.* — Achille Forti describes as Hetcroceras 

 schroeteri g. et sp. n., a new form collected by Prof. Scbroeter in the 

 Pacific Ocean, cbaracterised by the fact that the body is bifurcated from 

 the middle of the cell, and is elongated. In its other characters the new 

 form comes midway between the two genera Phalacroma and Amphi- 

 solenia. Like the members of the former genus, it has the margins of 

 the longitudinal furrows prolonged into wing-like structures supported 

 by spines ; while, as in Amphisolenia, it has the body elongated and 

 branched and the coat only slightly developed. 



Life-history of Gregarines.f— Prof. L. Cuenot has investigated the 

 Gregarines found in earthworms, in the domestic cricket, and in Peripla- 

 neta orientalis, which belong to the genera Monocystis (Lumbricns and Allo- 

 lobophora), Gregarina (Gryllus and Periplaneta), and Diplocystis (Gryllus). 

 In all these genera the life-cycle shows the following stages: — (1) A 

 growth-period, resulting in the conversion of the sporozoite into the 

 adult ; (2) a process of union, in which the two individuals become sur- 

 rounded by a common envelope ; (3) the appearance in each individual 

 of a micronucleus or segmentation nucleus, and the mitotic division of 

 this into many nuclei ; (4) the formation of sporoblasts by the accumu- 

 lation of cytoplasm round these nuclei ; (5) the conjugation in twos of 

 the sporoblasts which fuse to form zygotes; (6) the transformation 

 of the zygotes into sporocysts and the formation of eight sporozoites 

 within the sporocysts. At least in Gregarina and Diplocystis the sporo- 

 zoites do not divide when they enter the host, and give rise each to only 

 a single adult. The remarkable fusion of the sporoblasts was observed 

 most clearly in Monocystis, less certainly in Diplocystis. In these two 

 genera further, the absence of a true process of copulation during the 

 (permanent) union of individuals prior to sporulation was clearly proved. 

 In each of the united forms a segmentation nucleus appears, but there 

 is no interchange of nuclear fragments, nor any trace of polar body. 

 The segmentation nucleus is extra-nuclear in Diplocystis, but is formed 

 within the old nucleus in Monocystis. The nucleolus of the Gregarine 

 nucleus resembles in all respects the germinal spot of the egg in 

 Metazoa; it corresponds to the macronucleus of Infusoria. Iu the 

 cricket, Gregarina is an intestinal and Diplocystis a coelomic parasite, 

 the two being perfectly distinct and reproducing the type. 



Trypanosoma sanguinis in Batrachians.; — Karl Koninski finds that 

 this blood-parasite occurs in the Bufonidae as well as in species of Bana 

 and in Hyla arborea, but he has failed to find it in Pelobatidas. In frogs 

 and toads the probability of its occurrence increases with the age of the 

 animals ; it is commoner in males than in females, and is to be found at 

 all seasons of the year. Infected and sound animals may be kept 

 together for many months without the latter acquiring the parasite, and 

 the infected animals apparently retain their normal health. There is no 



* Ber. Deutsch. Bot. Ges., xix. (1901) pp. 6-7 ("2 figs.). 



t Arch. Biol., xvii. (1900, published 1901) pp. 881-652 (4 pis.). 



t Biol. Centralbl., xsi. (1901) pp. 40-::. 



