476 SUMMARY OF CURRENT RESEARCHES RELATING TO 



to his original view that it does not precede the act of impregnation, hut 

 is the result of it. There is no contrast, as Ntimec has suggested, between 

 the nuclear spindles of vegetative and those of generative cells ; but, on 

 the other hand, there are all grades of transition between multipolar and 

 bipolar spindles. In the root-tips of Ephedra major, in the early pro- 

 phase of division, a layer of delicate kinoplasm is formed about the 

 nucleus, and this layer soon collects at opposite poles of the nucleus, 

 where it appears as a pair of caps, the filamentous nature of which is 

 easily recognised. As the nuclear membrane disappears, threads grow 

 into the cavity, some of them becoming fast to the chromosomes, and 

 others forming continuous threads from pole to pole. 



The author comes to the conclusion that centrosomes are not present, 

 or at all events their presence has not yet been proved, in the higher 

 plants ; the kinoplasm appears to take their place, and to perform, in 

 the higher plants, the functions which it elsewhere shares with the 

 centrosome. The details are described of the mode of formation, in 

 some algae, of the swarm-spores on the blepharoplast. Strasburger 

 differs from Belajeff's interpretation of the blepharoplast as being 

 homologous to the centrosome. He regards the cilium-bearing portion 

 of the swarmspores of algae as homologous with the equivalent structures 

 in the antherozoids of the Characese and Archegoniatse, and partly also 

 with those of Gvmnosperms. While it would be difficult to doubt the 

 centrosome nature of the organ which gives rise to the tail of the animal 

 spermatozoon, it is not necessary to assume that the bodies at the base 

 of cilia in animals are centrosomes. The evidence does not point to the 

 existence of similar bodies at the base of the cilia of swarmspores and 

 gametes in plants. 



Development of the Connecting-Threads of the Cell-wall. * — Pur- 

 suing his researches on the origin and development of the connecting- 

 threads in the cell-wall, Mr. W. Gardiner states that they arise from the 

 median nodes of the fibres of the achromatic spindle. The nodes are 

 either (a) all continued as connecting-threads (endosperm cells of Tamus 

 communis) ; or (b) in part continued, and in part overlaid by superposed 

 lamellaa of cellulose membrane (endosperm cells of Lilium Martagon) ; 

 or (c) all overlaid (pollen-mother-cells and pollen-grains of Helleborus 

 foetidus). With regard to the genesis of the cell-plate, the author re- 

 gards it as originating not directly from the spindle-fibres, but indirectly. 

 It appears to consist of ordinary cytoplasm ; the primary cell-wall is 

 secreted from it as an equatorial membrane traversed by the nodes of 

 the achromatin spindle fibres. There appear to be grounds for regarding 

 this primary cell-wall as different in genesis and character from the 

 secondary formations which succeed it and arise from the general cyto- 

 plasm. The author is disposed to regard the cell-wall as fundamentally 

 of the nature of a mucilaginous secretion, and stratification as the neces- 

 sary accompaniment of the rhythmic periods of activity and rest of the 

 secreting protoplasm. 



Protoplasmic Connections in Viscum and Cucurbita. f — Herr F. 

 Kuhla finds that all the living cells of Viscum album are in communi- 



* Proc. Royal Boo., Ixvi. (1900) pp. 186-8. Cf. this Journal, 1898, p. 598. 

 t Bot. Ztg., lviii. (1900) 1" Abt., pp. 30-58 (1 pi.). 



