CHAi'. V THE ANTHOCEROTE^ 133 



Up to the point where the archesporium becomes divided 

 into two layers the cells appear alike ; but shortly after this 

 their walls begin to separate, and two distinct forms are re- 

 cognisable, arranged with much regularity in many cases, 

 although this arrangement is not invariable. Pretty regularly 

 alternating are groups of oval, swollen cells, with large nuclei 

 and abundant granular cytoplasm, and much more slender ones, 

 that may undergo secondary longitudinal divisions. The 

 latter have smaller nuclei and more transparent contents. 

 Examination higher up shows that the former are the spore 

 mother cells, the others the elaters, which here have the char- 

 acter of groups of cells, and do not develop the spiral thicken- 

 ings found in most Hepaticae. As these two sorts of cells 

 grow older they separate completely, and the spore mother 

 cells become perfectly globular. The sterile cells remain more 

 or less united, and form a sort of network in whose interstices 

 the spores lie. 



The development of the spores can be easily followed, at 

 least in most of the details, in fresh material, and on this 

 account it was among the first plants in which cell division was 

 studied.^ The mother cells in all stages can be found in the 

 same sporogonium, and on account of their great transparency 

 show the process of cell division very satisfactorily. The 

 nucleus, however, is small, and its behaviour during the cell 

 division is not so easy to follow. Strasburger ^' has described 

 this at length, and I can confirm his account. The mother cell, 

 just before division, is filled with colourless cell sap, and the 

 cytoplasm is confined to a thin film lining the cell wall. This 

 cytoplasmic layer is somewhat thicker on one side, and here 

 the nucleus is situated (Fig. 63, A). Lying close to the nucleus 

 is a roundish body, of granular consistence and yellowish green 

 in colour. This is a chloroplast, which at this stage is less 

 deeply coloured than later. The chloroplast contains a number 

 of granules, some of which are starch. The cell increases 

 rapidly in size, and the nucleus, together with the chloroplast, 

 moves away from the ^^'all of the cell toward the centre, where 

 they are suspended by cytoplasmic threads. The chloroplast 

 next divides into two equal portions, which move apart (Fig. 

 63, B), but remain connected by the cytoplasmic filaments. 

 They approach again, and each dividing once more, the four 



^ -Strasburger (9), p. 158. - Strasburger, I.e. p. i6r. 



