438 NOTES AND MEMORANDA. 



parasitic alga, Callitliamnion memhranaceum and Oscillana spongelice 

 (n. sp.). 



Protozoa. 



Evolution of the Infusoria from the Lower Protozoa. — In some 

 speculative observations on the probable steps in and causes of the 

 evolution of the Infusoria from the lower Protozoa* Mereschkowsky 

 remarks upon the (as a general rule) total absence of symmetry in the 

 Infusoria, and considers that this is explained by the close genetic 

 connection between that group and Amoehce. The first step in the 

 differentiation of the latter was probably a hardening of the superficial 

 layer of protoplasm, and with this was connected a proportional 

 thinning and lengthening of the pseudopodia, and a slowing of the 

 animal's movements. With the gradual induration of the superficial 

 layer of protojilasm, there seems to have come about a greater and 

 greater restriction of the area suitable for the inception of nutriment ; 

 in this way the infusorial mouth was produced. But as the in- 

 gestive area became less, it became more and more necessary that the 

 animal should have the means of rapid locomotion, and so be able to 

 make up, by active foraging, for the lost power of taking in any 

 suitable food-particle which might happen to come in contact with 

 any part of its surface. In response to this want, it would seem that 

 the variously disposed cilia and flagella of the Infusoria came into 

 existence by the action of natural selection. 



Acinetae and Vorticellse. — Biologists, as is well known, have 

 never yet accepted the views of Stein as to the Acineke being stages 

 of development of Vorticcllce, &c., mainly from the fact that his 

 observations have not been confirmed by other observers. Mr. H. E. 

 Forrest, one of the secretaries of the Birmingham Natm-al History and 

 Microscopical Society, in describing what he terms " Acinetation " in 

 the Vorficelhv,'\ states that " last October, while examining some 

 AcineicE, he saw a small Vorticella burst from the body of one of them 

 and swim away." 



Researches on the Acinetae. — M. Fraipont, in continuation of the 

 results of his investigations on the Acinetce found on the Ostend coast, 

 publishes three parts of his memoirs, | in which he deals with the 

 structure of some well-known and of some new species, and also with 

 the general characters of the group ; to this last we will first address 

 ourselves. 



Skeletal memhrane (Hertwig). — The presence of this structure and 

 its morphological characters have been the subject of considerable 

 doubt and dispute ; Claparede and Lachmann regarded it as a calyci- 

 form covering of resistant character ; Stein asserted that in addition 

 to this there was an internal membrane, while Hertwig has drawn 

 attention to the differences presented by Acinefce as compared with 

 Pudoplmja ; in Acineia Fraipont always found an internal membrane 

 covering the surface of the protoplasm, at all points where this was- 



' ' Arch. f. IMikr. Anat.,' xvi. (1879) 153. 



t ' Midland Naturalist,' 11. (1879) 88. 



X 'Bull. Ac. Koy. Belg.,' xlv. (1878) 217, 287, 475. 



