2 J. BURTON ON THE REPRODUCTION OF MOSSES AND FERNS. 



and having once become thoroughly acquainted with the typical 

 structure and methods it is easy to understand the analogies 

 and the processes in the whole of the Bryophyta and Yascular 

 Cryptogams. 



Looking at the vegetable kingdom in general we see that 

 plants have an immense variety of methods of propagating 

 themselves. They may do so, for instance, by means of portions 

 broken off, by division of the root stock, by small bulbs produced 

 upon various parts, by runners and offsets, and so on. But 

 these plans, although exceedingly efficient in increasing the 

 number of individual plants, can hardly be looked upon as 

 reproduction except in the widest sense. They provide for the 

 extension of the individual, but as there is usually no return to 

 and development from the simpler form of the single cell, we are 

 justified in regarding such instances as not being reproduction in 

 its true, or, at least, in its narrower sense. Confining ourselves 

 to the more restricted meaning of the word we find two main 

 systems of reproduction, — (1) the sexual, which prevails — to out- 

 ward appearance, at any rate — almost exclusively in the higher 

 plants, where the life-cycle consists of a mature plant which 

 produces seeds, which in due course ripen, germinate, and give 

 rise to a new individual like the parent ; and (2) the non-sexual 

 system by means of spores, which give rise to an organism like 

 that from which they are derived, this form of reproduction 

 being mainly prevalent in the lower orders. In the two groups, 

 the mosses and ferns, now under consideration, the most 

 characteristic feature is that both these methods are developed 

 to their fullest in one life-cycle. This life-cycle as a whole is. 

 spoken of as an alternation of generations. The term does not 

 well express the truth, but it is in general use and has some 

 conveniences. It implies that, where it exists, a plant does 

 not reproduce its own likeness in its immediate descendants, but 

 another form, which, again, instead of giving rise to progeny like 

 itself, reproduces the form of its own parents. Moreover, one of 

 these two forms is dependent for its origin on sexual reproduction, 

 w r hile the other is produced non-sexually. 



Taking the moss first, it will be as well to commence with 

 the part of the cycle which is generally known, and then discuss- 

 that which is less evident. The moss plant bears the sexual 

 organs in the alternation of generations, and is known as the 

 "oophyte"; this is an awkward term, but it will save some 

 trouble further on to become acquainted with it now. It simply 



