ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 441 



Life-History of Lankesterella minima.*— E. Hintze has investi- 

 gated this haemospore parasite of the frog's blood, perhaps better known 

 as Drepanidium. He describes the structure, mode of life, the schizogony, 

 the sporogony, the formation of micro- and macro-gametes, the matura- 

 tion of the latter and their fertilisation by the former. He also discusses 

 the mode of infection and the different species. Many gaps in our 

 knowledge of this common form are removed by this research. 



Progressive Movement of Gregarines.f — H. Crawley has studied 

 the gliding movements of Stenophora juli and Echinomera hispida. One 

 kind of movement, which consists of contractions of the body, is readily 

 explained by the existence of " the muscular layer," but the other kind, 

 of movement, in which the animal glides along, usually, it is said, " with- 

 out the slightest bodily movement," has been for many years a riddle. 



In 1894 iSchewiakoff advanced the theory, supported by careful 

 studies, that Gregarines progress by means of the extrusion of gelatinous 

 fibres, derived from a layer between the cuticle and the ectoplasm. He 

 supposed that they form a hollow cylinder behind the animal and ac- 

 quire a certain amount of rigidity, that the posterior end of this cylinder 

 impinging upon some resistant hody, becomes fixed, and that the Grega- 

 rine is pushed passively forward as the extrusion continues and the 

 cylinder lengthens. 



Crawley cannot accept Schewiakoff 's theory. The progression of 

 Gregarines is effected in a manner somewhat as follows : — The muscular 

 impulse, starting backward from the region of the septum, necessarily 

 causes the contact of the Gregarine (with the cover- glass) to be different 

 in this region from what it is in the more posterior parts. Further, 

 since the transverse movement takes place at the same time as the back- 

 ward movement, that part of the Gregarine's surface where the contact 

 relations are temporarily different moves not only backward, but from 

 side to side as well. It is not difficult to see how movements of this 

 sort may produce locomotion, when it is recollected that Gregarines are 

 sticky. 



This explanation is based on the fact that Gregarines possess a well- 

 developed muscular system, while the theory of a passive locomotion 

 by means of the extrusion of gelatinous threads is without parallel in 

 the animal kingdom. 



Cabbage and Cancer. :J — L. Feinberg describes the peculiarities 

 especially as regards nucleus, of the amoeboid organism — Plasmodio- 

 phora brassicse — causing cabbage-hernia ; and hints at the possible 

 •occurrence of a similar organism at work in human carcinomata. 



* Zool. Jahrb., xv. (1902) pp. 693-730 (1 pi.). 



t Proc. Acad. Nat. Sci. Philadelphia, 1902, pp. 4-20 (2 pis.). 



X Ber. Deutsch. Bot. Ges., xix. (1901) pp. 533-6. 



* I t^» t m 



August 20th, 1902 2 g 



