ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 905 



classification, the characters of the spicules are described. Useful 

 tables give the synonyms of the very various names aj^plied to these 

 bodies, and the author describes his system of formulation or rather 

 stenography. 



Protozoa. 



Nuclei of Infusoria.* — In several Infusoria Dr. C. F. Jickeli has 

 observed the extrusion of " polar bodies," a process entirely similar to 

 that known to occur in the ovum ; as in the case of the ovum these 

 bodies are extruded from the greatly enlarged nucleus. In Stijlonychia 

 mytilus and other forms, the same observer has noted a multiuuclear 

 condition produced by the division into a number of irregularly 

 sized fragments of the original nucleus ; this may occur previously 

 to any conjugation ; it was found possible to produce the same eifect 

 by artificial means ; examjjles of Par amcecium caudatum kept for eight 

 days in the dark always showed this phenomenon, but the nucleolus 

 remained unaltered. On the other hand a condition occasionally 

 supervenes where the nucleus has entirely disappeared. During 

 division the so-called nucleolus assumes the spindle form, but the 

 nucleus does not ; neither of these bodies however initiate cell- 

 division which is always recognizable in the first place by the changes 

 in the cell-protoplasm itself. The conjugation of Infusoria is a 

 subject which has engaged the attention of many naturalists and their 

 results are very conflicting ; it appears that in some exceptional cases 

 three individuals may fuse together, though more generally two ; 

 when this has taken place the Infusorian remains motionless for a 

 time ; the changes which follow commence in the cell-protoplasm and 

 only subsequently extend to the nucleus ; in those forms which 

 possess a nucleolus the latter becomes widely separated from the 

 nucleus at the commencement of conjugation or even before, but is 

 connected with it by a fine thread ; the nucleolus divides into a 

 number of bodies, and in Paramcecium at any rate it is quite clear 

 that there is an exchange between these two individuals of their 

 nucleolar bodies ; no such exchange was observable in the case of 

 the nucleus. 



New Infusorian— Ctedoctema acanthocrypta.t — Dr. A. C. Stokes 

 Las found on Lemna an Infusorian to which he gives the above name 

 and the following diagnosis : — 



Ctedoctema, gen. nov. (Greek, ktedon, a comb ; ktema, a possession). 

 Animalcules free-swimming, more or less ovate, persistent in shape, 

 entirely ciliate ; oral cilia diverse to those of the cuticular surface ; 

 oral aperture ventral, located at the posterior termination of a longi- 

 tudinal, ciliated, adoral depression or groove which bears on its riglit- 

 hand border a row of large acutely curved setose cilia, gradually 

 diminisliing in length towards the oral aperture which they surround, 

 and with their distal extremities conspicuously thickened ; several 

 long setose hairs projecting from the posterior extremity of the body, 



♦ Zool. Anzeig., vii. (1884) pp. 401-7. 

 t Ainer. Natural., xviii. (1884) pp. 059-60 (4 figs.). 

 Ser. 2.— Vol. IV. 3 O 



