VEGETATIVE PROPAGATION. 723 



In the true Mosses almost any cell of the roots, leaves and shoot-axes, 

 and even of the immature sporogonium, may grow out under favourable conditions, 

 become rooted, form new shoots, and give rise to an independent living plant. 

 Besides this, however, there are some species, like the Tetraphis illustrated in Figs. 

 406 and 407, which produce, in addition to true organs of reproduction, peculiarly 

 formed gemmae in special receptacles, and these contribute essentially to the 

 multiplication of the individuals. The Liverworts behave similarly : in many of them 

 not only are the individual cells of the leaves able to separate and germinate, but 

 here also various species are found which give rise to multicellular complex gemmae 

 in special receptacles, of which the Marchantia figured on page 69 may serve as the 

 most convenient and best known example. 



All these different cases, which could be increased by many others more or less 

 abnormal, are properly left out of account when referring to reproduction in the 

 narrower sense : they may be collated under the name of organs for vegetative 

 propagation, in contrast to the reproductive organs in the stricter sense of the word. 

 All these vegetative organs of propagation are fundamentally nothing more than 

 parts of the vegetative body itself, or at any rate are not essentially distinct from 

 it: their organisation presents, in contrast to the rest of the vegetative body, 

 nothing essentially new or abnormal, and especially it may here be insisted upon 

 that by means of merely vegetative propagation the properties of the parent plant 

 are usually transmitted to the descendants much more strictly than is the case 

 with reproduction in the narrower sense of the word — a point to which I shall 

 return. 



The proper reproductive organs, on the contrary, differ from the vegetative 

 organs in their whole organisation and development, and particularly in the manner 

 and means by which they fit into the life-history of the plant. 



The true reproductive organs, again, are distinguished from merely vegetative 

 organs of propagation by the fact that they serve exclusively and only for the purpose 

 of reproduction. They are in no way concerned (apart from a few exceptions such as 

 Spirogyra and other Conjugatse) either before or afterwards in the function of nutri- 

 tion, or in the simple maintenance of the existing individual : their proper task is 

 that of reproduction. But of course, here, as in the whole kingdom of organic life, no 

 perfectly strict distinction can be maintained. Here again our ideas are best de- 

 veloped in considering the most sharply characterised forms — i. e. typical forms. With 

 these, just as was found to be the case with the vegetative organs, two categories of 

 more or less deviating forms of organs are connected ; on the one hand the rudi- 

 mentary organs, which we may regard as incomplete but archaic, and on the other 

 the degraded organs which have degenerated, so to speak, subsequently from the 

 typical height of organisation. 



In the case of the vegetative organs, shoots and roots, we had above all to take 

 cognisance of the remarkable fact that organs of like genetic significance may assume 

 different forms in order to fulfil different functions. In the case of the proper organs 

 of reproduction we find exactly the opposite : their function, the origination of new 

 individuals, always remains the same, since this is, as already mentioned, their single 

 object. Nevertheless, if we take in review the whole vegetable kingdom, proceeding 

 from the simplest plants, the reproductive organs assume very various forms; so- 



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