CHAPTER XV 



SUMMARY AND CONCLUSIONS 



T]ie Interrelations]iips of the ArdiegoniatcB 



It is pretty generally conceded that the origin of the whole 

 archegoniate series is to be sought somewhere among the green 

 Algs, and that on the whole ColeocJicete is, perhaps, the form 

 which is nearest to the simplest Muscineae. While the 

 Characeae, as we have seen, approach the latter more nearly 

 in the structure of the sexual organs, yet the character of the 

 vegetative parts is so different from that of any of the Muscineae, 

 and the sporophyte is so simple, that any close relationship of 

 the two groups is hardly probable. At best, the connection 

 between any known Alga and the Muscineae is a very remote 

 one. 



From a study of the facts presented in the foregoing pages, 

 the conclusion has been reached that the Hepaticae are not only 

 the most primitive of the existing Archegoniatae, but are also 

 the forms from which all the other groups have descended. 

 When, however, the question arises as to which of the existing 

 groups of Liverworts is the most primitive, the matter is not so 

 easy to settle. Thus while Riccia undoubtedly has the most 

 primitive sporophyte, the gametophyte shows a much higher 

 degree of differentiation than is found in miost anacrogynous 

 Jungermanniaceae and the Anthoceroteae. The latter group, 

 while retaining an extremely simple type of gametophyte, has 

 the sporophyte developed beyond that of any other Bryophyte. 



It will be remembered that in the germination of most 

 thalloid Liverworts (and occasionally in the foliose forms as 

 well) the occurrence of a single two-sided apical cell is quite 

 general, although this may be absent from the fully-developed 



