ZOOLOGY AND BOTANY, MICROSCOPY, ETC 3 67 



inclusions, and so on. The nucleus shows an " internal l)odj," rich in 

 chromatin. The " accessory l)ody," which Schaudinn described, is dis- 

 cussed at length. It has centrosomes and a " middle piece," which 

 may be regarded as a specialized second nucleus. The process of 

 division is described, and the formation of flagellate gametes in P. 

 'pigment if era. A comparison is made between the two parasitic species 

 and Schaudinn's P. eilhardi. Attention must be drawn to the striking 

 and interesting figures accompanying the paper. 



Monograph on Acinetaria.* — B. Collin deals with the morphology, 

 physiology, and taxonomy of the Acinetaria. He describes the minute 

 structure of the ectoplasm and the endoplasm, the tentacles, the nuclei, 

 the mode of fixation, the production of " embryos " and vermiform 

 bodies, the occurrence of fission, the details of conjugation, the encys- 

 tation, the nutrition, the movements, the inter-relations with other 

 creatures. 



Eight families are recognized — Acinetidse, Discophryidfe, Dendro- 

 somid^e, Dendrocometidse, Ophryodendridge, Podophryid^, Ephelotidse, 

 and Hypocomidse. Collin thinks that the origin of the Acinetaria 

 must be looked for among the Yorticellids. We cannot do more than 

 call attention to this very valuable monographic study. 



Reactions of Peranema.f — S._0. Mast has experimented with this 

 colourless cigar-shaped Flagellate. It usually moves in contact with 

 the substratum by means of a combination of wave-like contractions 

 of the body and the flagellum, but it can move by the action of either 

 alone. The action of the flagellum is ordinarily the more effective. 

 When very strongly stimulated, as by the addition of chemicals, it 

 swims through the water free from the substratum, much like Euglena. 

 This is rarely seen in normal environment. 



When crawling, the flagellum projects straight forward ; only the 

 tip is active, and the organism usually moves on a straight course with- 

 out rotation on the long axis. When swimming, the entire flagellum 

 beats in a rotary wave-like fashion, and the body rotates on its long axis 

 and takes a spiral course. The animal does not orient itself. It 

 responds to light very indefinitely, if at all. 



If the flagellum comes into contact with an object, the animal bends 

 always toward the larger lip, then proceeds on a new course more 

 or less at right angles with the old. The same response can be in- 

 duced by constant stimulation of any part of the body, or by chemical 

 stimulation. There is sometimes local contraction at the point of stimu- 

 lation, but this does not apparently influence the direction of motion. 



If the body becomes lodged or entangled, the tip of the flagellum 

 gradually beats more and more vigorously. If this does not free the 

 animal it bends towards the larger lip, so as to extend the flagellum in 

 a different direction. Bending the body, and beating of the flagellum 

 alternate until the animal becomes free or fatiofued. This behaviour 



'•&" 



* Arch. Zool. Exper., li. (1912) pp. 1-457 (6 pis. and 111 figs, 

 t Journ. Animal Behaviour, ii. (1912) pp. 91-97 (1 fig.). 



