632 MICEOSCOPIC FORMS OF VEGETABLE LIFETHALLOPHYTES 



antherozoids, but minute rounded particles, known as pollinoids or 

 * spermatia,' having no power of spontaneous movement. Some- 

 times on the same individuals as the antherids, and sometimes on 

 different ones, are produced the female organs, which curiously 

 prefigure the pistil in flowering plants. This organ is known as 

 the procarp, and consists, in its simplest form, e.g. in Porphyra, the 

 ' purple laver,' of a single cell with a lateral hair-like appendage, the 

 trichogyne. In the higher forms it is composed of one or more 

 fertile cells constituting the carpogone,, and one or more sterile cells 

 which make up the trichophore, and convey the fertilising substance 

 from the trichogyne to the carpogone. Fertilisation is effected by 

 the attachment of one of the pollinoids to the trichogyne, the walls of 

 which are absorbed at that spot, so that the fertilising material passes 

 down its tube to the trichophore, and thence to the carpogone ; one 

 of the cells of the carpogone contains the oosphere, which, after 

 fertilisation, breaks up into a number of carpospores ; round these 

 is frequently formed a hard investment, and this structure is then 

 known as a cystocarp ; from it the carpospores ultimately escape, 

 and then germinate. In the true Corallines, which are Floridecc 

 whose tissue is consolidated by calcareous deposit, not only the 

 tetraspores, but also both kinds of sexual organ, are produced in 

 cavities or conceptacles, imbedded in the thallus or forming wart-like 

 swellings ; the female conceptacle opens by a terminal orifice or 

 ostiole ; the pollinoids are furnished with wing-like appendages. 

 In a considerable number of the red seaweeds, as, for example, in 

 Dudresnaya, the process of fertilisation is more complex than this, 

 and consists of two distinct stages. First the trichogyne is impreg- 

 nated by the pollinoids ; and secondly, the fertilising principle is 

 then conveyed from the trichophore-cells at the base of the tricho- 

 gyne to the cells which ultimately produce the carpospores, and which 

 may be at a considerable distance from the trichogyne, even on a 

 different branch. This transference is effected by means of long 

 simple or branched tubes which are known as ' fertilising tubes.' 

 The late Professor F. Schmitz held that, in the higher Floridea?, 

 there are two acts of fertilisation, that of the pollinoid with the 

 trichogyne, and that of the fertilising tube .with the cells which produce 

 the carpospores ; but this view is not accepted by all authorities ; 

 and it is doubtful whether more than one true act of fertilisation, 

 i.e. the fusion of male and female nuclei, takes place. The sexual 

 mode of reproduction has, however, at present been observed in 

 comparatively few species of seaweed ; and,, considering the number 

 of species of Floridece found on our coasts, there is no branch of 

 microscopical observation which is more likely to reward the young 

 investigator with new discoveries. 



