616 SUMMABY OF CUKRENT RESEARCHES RELATING TO 



aperture or cytopyge, the nature and functions of their contractile 

 vacuoles or vesicles, nuclei or endoplast, and nucleoli ; their colouring 

 matters, accessory structures (such as trichocysts), and the phenomena 

 of reproduction whether by binary division or fission ; external and 

 internal gemmation, sporular multiplication or sexual reproduction ; 

 also a discussion of the affinities of the Infusoria to the higher 

 zoological groups, their distribution, and mode of collection and 

 preservation, with a very brief section on methods of investigation. 

 Chapter IV. is a summary of what has hitherto been written on 

 " Spontaneous Generation." Chapter V. contains an extensive dis- 

 cussion of the nature and affinities of the sponges and their near rela- 

 tionship to certain of the Infusoria Flagellata — the Choano-Flagellata, 

 the author considering that "scarcely a shadow of doubt even is 

 admissible concerning the intimate and thorough-going relationship 

 that subsists between one and the other." Chapter VI. recapitulates 

 the systems of classification hitherto adopted, from 0. F. Miiller, in 

 his 'Animalcula Infusoria' (1786) to that of the author. Chapter 

 VII. and succeeding chapters contain the systematic descriptions of 

 the three classes of Flagellata or Mastigophora, Ciliata or Trichophora, 

 and Tentaculifera. 



Amongst the new genera and species may be mentioned * Dallin- 

 geria Drijsdali (a Flagellate), which commemorates the remarkable 

 observations of the two microscopists whose names are adopted. 



Variety of Stentor.f — Professor Leidy describes a variety of 

 Stentor existing in attached groups, of a lilac or amethystine colour, 

 which may be named S. amethystinus. It is probably a variety of 

 S. igneus, which Ehrenberg describes as bright yellow or vermilion, 

 Stein as blood red, or often lilac-coloured, or vermilion to brownish 

 red. Ehrenberg found it attached to Hottonia. Stein says he never 

 saw it fixed, but always swimming. 



The new variety was abundant, and invariably found in conspicu- 

 ous groups, visible to the unaided eye, and when detached, though 

 the animals swam about actively, they were not only disposed to 

 become fixed, but they actually gathered together in groups. They 

 all contained an abundance of chlorophyll, apparently derived from 

 food, but the exterior structure was invariably of a distinct amethystine 

 hue, dependent on fine molecules. The colour was more pronounced 

 in the longitudinal bands approaching the peristome. The nucleus 

 was spherical. In the attached state, when the animal was fully 

 extended and presented a trumpet shape, it was 0*6 mm. long by 

 0' 18 mm. wide at the peristome. This was a common size, but some 

 measured were • 84 mm. long. In the conical form when swimming, 

 individuals ranged from 0*27 to 0*42 mm. long. In the most 

 contracted condition of oval shape, they measured 0*18 mm. long by 

 0' 15 mm. broad. The nucleus 0* 03 mm. in diameter. 



Ehrenberg and Stein give for S. igneus one-sixth of a line length, 

 so that the variety indicated would appear to be much longer. 



* Loc. cit., pp. 309-12. 



t Proc. Acad. Nat. Sci. Phila., 1880, pp. 15G-8. 



