Cytologie und Befruchtung. 485 



warteten Ergebnis, dass, wenn nicht alle, so doch die Haupt- 

 masse des Protoplasma, welches die Intercellularen auf Schnitten 

 •durch frische Kotyledonen gequollener Samen und junger Keim- 

 pflanzen erfüllt, aus den Nachbarzellen stammt und bei der 

 Herstellung der Schnitte in die Intercellularen gelangte, indem 

 es kapillar in die geöffneten Intercellularen eingesaugt wurde. 

 Somit ist das Vorkommen von intercellularem Protoplasma 

 wieder zweifelhaft geworden. M. Koernicke. 



Lawson, A. A., The Gametophytes, Fertilisation and 

 Embryo of Cryptomerla Japonica. (Annais of Botany. 

 Vol. XVllI. 1904. p. 417—444. With PI. 27—30.) 



In the germination of the pollen grain it is stated that no 

 vestigial prothallial cells are formed. The nucleus of the grain 

 divides once, to form the tube nucleus and the generative 

 nucleus. Later on the latter divides, and a stalk nucleus, 

 together with the generative cell is the result. Generative 

 cell increases greatly in size, and finally its nucleus divides; the 

 resulting cells separate, and form the two male gametes. 



In the ovule there are present 3 or 4 spore mother cells; 

 each of these gives rise to four cells, but only one of the 

 12 or 16 Potential spores developes further. The one which 

 persists increases greatly in size, the nucleus divides many 

 times, and the central portion of the spore is occupied by a 

 large vacuole, The nuclei at this stage lie free in the peri- 

 pheral protoplasm. Soon^ however, walls are formed which 

 partition the protoplasm, but the cells are open towards the 

 interior-vacuoie of the spore. The author terms these the 

 primary prothallial cells, meaning there by the same things as 

 those designated by Sokolowa as „alveoli", and by Coker 

 as „prothallial tubes". Nuclear division continues to go on 

 within these areas, but no cell walls are at first formed. These 

 are stated to arise later in a remarkable fashion. When a 

 number of free nuclei have been produced, a peculiar mitosis 

 is described as occurring. Instead of cell walls being formed 

 during the later phases in the equatorial plane of the spindle, or 

 eise in a way altogether independant of the mitosis (as for 

 example in the eggs of Fucus and many other cases) the 

 spindle fibres are said to arrange themselves in hollow spheroids, 

 and where the spindles of adjacent pairs of nuclei come in 

 contact they give rise to walls. Thus the cells which are 

 formed in this remarkable way all contain two nuclei; that is, 

 the pair of nuclei which, at first situated at the ends of the 

 spindle, have sunk into the spherical space included by the 

 Gurions arrangement of the fibres at the telophase of mitosis. 

 Sufficient details are not given to enable a critical reader to 

 follow^ the whole series of phases as fully as would be desi- 

 rable having regard to the peculiarity of the phenomenon 

 described. By further division, which apparently proceeds on 



