ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 05 



The growing egg becomes more and more filled by yolk-granules, but 

 the nucleus never disappears completely, tbougb it often approacbes tbe 

 surface. Tbis position is, no doubt, to be correlated with tbe extrusion 

 of tbe polar globule?. 



Spermatogenesis is on tbe second type of Polejaeff. There is no 

 special covering-cell or primitive sperm-cell. In division, karyokinesis 

 was frequently observed. 



Protozoa. 



Conjugation of Paramecium.* — M. E. Maupas finds that tbe con- 

 jugation of male and female pronucleus as previously described by him 

 was admirably figured by Balbiani in 1858. f Maupas had known the 

 compressed summary in the Comptes Bendus, but not the full research 

 with plates. Balbiani figured the process beautifully, but regarded 

 what he figured as the longitudinal division of tbe micro-nuclear 

 (nucleolar) element. x\t tbis time only Warneck, in another overlooked 

 'research (1850), had observed the conjugation of pronuclei in the ova of 

 Lymnseus. This was reobserved in 1874 by Biitscbli in a nematode. 



The phenomena described by Maupas have now been observed in 

 nine ciliated Infusorians : Paramsecmm caudatum, P. aurelia, Stylonichia 

 pustulata, Onychodromus grandis, Spirostomum teres, Leucophrys patida, 

 Euplotes char on, Loxophyllum fasciola, and Paramsecium bursaria 

 (Balbiani). 



M. Maupas reaffirms bis certitude as to the seven first stages in the 

 complex process. The micro-nucleus increases, divides, eliminates ele- 

 ments, differentiates, elements are exchanged, and two portions (male and 

 female) conjugate. A single nucleus results, and this divides twice. 

 The further reconstitutive changes are less certain. He is, for instance, 

 in doubt as to the persistence of the original nucleus. 



New Fresh-Water Infusoria. $ — Dr. A. C. Stokes describes a number 

 of new fresh-water Infusoria. Hexamita spiralis, from the intestinal 

 canal of the tadpole of the common toad, differs from previously observed 

 species by the presence of two contractile vacuoles and the spiral dis- 

 position of two of the anterior flagella ; Petalomonas dorsalis which has 

 a conspicuously developed centro-dorsal upright plane, and P. sulcata 

 are both from pond water. A new genus, Urceolopsis, is established for 

 Urceolus sabulosus Stokes ; in it tbe entire cuticular surface is more or 

 less covered by adherent, irregular, and angular sand-grains. Trachelo- 

 monas urceolata, T. verrucosa, and T. acanthostoma ; Anisonema solenota, 

 Protopteridinium limbatum, and Holophrya ornata follow. Saprophilus is 

 a new genus for S. agitatus sp. n. ; these animalcules are essentially 

 scavengers which, rapidly undergoing fission, swarm in crowds round and 

 within the dead bodies of various small aquatic animals. Bothriostoma 

 undulans g. et sp. n., is a heterotrichous form, in which the left-hand 

 border of the peristome carries a series of large cilia, while tbe posterior 

 portion of the right-hand margin supports an undulating membrane. A 

 second species of Hymenostoma, H. magna f«)«|, is described ; it may be 

 easily distinguished from H. hymenophora by its larger body ; conjugation 

 has been observed, union taking place between the ventral surfaces of 

 the right-hand body margins. There are four new spepies of Vorticella, 



* Comptes Rendus, cv. (1S87) pp. 955-7. See tbis Journal, 1887, p. 973. 

 t Ibid., xlvi. (185S) p. 628, and Journ. de Pbvsiol., i. (1858) p. b47, pi. iv. 

 j Proc. Amer. Phil. Soa, xxiv. (18S7) pp. 241-55 (1 pi.). 

 1888. F 



