CHAP, i.] Sexuality in Cryptogams. 439 



where it might be presumed that the fertilisation by the 

 spermatozoids takes place ; and as the history of the germi- 

 nation of the rest of the vascular Cryptogams was to some 

 extent known through the earlier labours of Vaucher and 

 Bischoff, the organs of fructification of these plants might now 

 be sought, where they are really to be found. But an erroneous 

 idea respecting the meaning of the small spores of the Rhizo- 

 carps propounded by Schleiden had first to be put out of the 

 way, and this was done by an appeal to the discovery of Nageli 

 mentioned above and by the investigations of Mettenius. Then 

 in 1849 Hofmeister supplied a connected description of the 

 germination of Pilularia and Salvinia, in which the decisive 

 points as regards the sexual act were clearly set forth, and the 

 connection of the spermatozoids with the fertilisation of the egg- 

 cells in the archegonium was established. He did the same 

 for Selaginella, which is very unlike the Rhizocarps and Ferns, 

 and in which the spermatozoids are developed from smaller 

 spores, and fertilise the egg-cells in archegonia formed in the pro- 

 thallium of the large spores. By comparing the processes of 

 germination in these plants with those of Ferns and Mosses, 

 he succeeded in throwing entirely new light on the whole of the 

 morphology of these classes of plants, and thus made it possible 

 for the first time to compare them with one another and with 

 the Phanerogams, and to form a 'right estimate of the sexual 

 act in the Muscineae and Vascular Cryptogams in its relation 

 to the history of the development of these plants. Hofmeister 

 arrived at the following conclusion from his observations in 

 1 849 : ' The prothallium in the vascular Cryptogams is the 

 morphological equivalent of the leaf-bearing Moss-plant, while 

 the leafy plant of a Fern, of a Lycopodium and a Rhizocarp 

 answers to the capsule of the Moss. In Mosses as in Ferns 

 there is an interruption of the vegetative development by 

 sexual procreation, an alternation of generations; this takes 

 place in the Vascular Cryptogams very soon after germination, 

 in the Mosses much later.' The vast importance of this dis- 



