Notes. 
583 
was taken, that then the second step consisted in the formation of 
stationary spores arising by a tetrad division. With such assumptions, 
the transition to the simple Liverworts — e.g. Riccia , does not appear very 
great, and, starting from this form, the different series included in the 
Bryophyta may be derived. Though we have thus gained certain 
connecting points for the phylogeny of the Mosses, the question as 
regards the Ferns, in which the fertilized ovum develops into the leafy 
plant, is in quite another position. It has been recognized on many 
sides how great a contrast there is between Mosses and Ferns. The 
common peculiarity in the structure of the archegonium might be 
a purely parallel development without its necessarily indicating any 
phylogenetic connexion. It is not my purpose to enter now upon 
these difficult questions, the less so since they will be dealt with here 
from an official quarter. They deal with the most interesting, but 
also the most obscure, points in the phylogeny of the vegetable 
kingdom. For the spot where the first indication of a Fern-sporophyte 
appeared was the birthplace of the vastly-developed series of the 
Phanerogams. The Thallophytes hitherto known do not give the 
least clue to the discovery of that spot. 
GEORGE KLEBS, Tubingen. 
ALTERNATION OF GENERATIONS IN THE ARCHE- 
GONIATAE. — One of the most important facts in the morphology 
of all plants higher than Thallophytes is the occurrence in their 
life-history of two alternating stages, which differ widely from each 
other both in structure and reproduction. Of recent years advances 
in our knowledge in several distinct departments of botanical investiga- 
tion have raised anew the question of the nature of this Alternation 
of Generations. The subject has been discussed from two very 
different standpoints in the Presidential Addresses to this Section 
of the British Association this year and at the Liverpool Meeting 1 . 
These expressions of opinion by Dr. Scott and Professor Bower 
render an introductory paper to this discussion in one sense superfluous. 
While, however, repetition of much that has been already said is 
unavoidable, the existence of such diverse views suggests a slightly 
different treatment of the question, which may be useful for the 
1 The existence of these recent statements of the problem renders references to 
the literature of the subject unnecessary. 
R r 
