REPRODUCTION 209 



complicated systems of metabolism and conduction, may be developed. 

 Chlorophyll is present in the higher groups, and the vegetative processes 

 are very similar to those which we have before considered. In other 

 classes chlorophyll is wanting, and the plants are hence unable to 

 perform the constructive assimilation which we have found among 

 most Phanerogams, but ready formed compounds, or those readily 

 broken down into the required form, must be found for their support. 



Reproduction. — We find among the reproductive processes in Crypto- 

 gams almost as great a diversity as among their other characters. Not 

 only do both vegetative and sexual forms exist, as among Phanerogams, 

 but while many groups exhibit both forms, others possess only the 

 vegetative. Among the higher classes, the vegetative forms of repro- 

 duction are quite elaborate, involving phytomer-like parts, either singly 

 or in bud-forms, while in other cases it can occur by single leaves or 

 parts of them. Among the lower classes, where phytomers and leaves 

 are unknown, these processes are necessarily simpler. In their higher 

 members, masses of tissue, often specially constructed, called gemmae or 

 buds (but of course not conspicuously homologous with the buds which 

 we have studied), separate to form new plant-bodies, the process being 

 called gemmation. In other cases the process is the simplest possible 

 one of cell-division. 



Sexual reproduction among cryptogams is too variable to be here 

 considered, even in a general way. In no Cryptogamous plant, how- 

 ever, is there developed any structure which combines the varied 

 functions of that which among Phanerogams is called the flower. The 

 extension of this term to any reproductive organ of the former group, 

 merely because certain homologies have been discovered between 

 them and the flower, is misleading, as it tends to magnify slight resem- 

 blances into a higher degree of importance than great differences, and 

 it furthermore subverts the original and fully established meaning of a 

 common term into a new, even if it were a strictly accurate, application. 



When alternation of generations occurs, with the production of 

 distinct gametophytes, the male cells, in the form of antherozoids, are 

 usually provided with some independent power of locomotion for 

 reaching the female element, known as the Central Cell, within a distinct 

 organ called by various names. 



It has already been stated that the spores germinate for the production 

 of these gametophytes in any suitable soil, and that the resulting 

 embryo continues its development without passing into a resting or 



seed stage. 

 14 



