NOTES. 
[The following paper was read by the late Mr. Vaizey before 
Section D of the British Association at the Manchester meeting in 
1887. As only a very short abstract appears in the Report of that 
meeting (p. 771), the Editors have thought it not inappropriate to 
publish the paper in exlenso . ] 
ALTERNATION OF GENERATIONS IN GREEN PLANTS. 
In drawing your attention to the subject of alternation of generations 
in the Green Plants my object is two-fold : — 
First, to place before you a view of the origin of alternation of 
generations, which, although I do not claim that it is quite original, 
has not, so far as I know, been distinctly formulated before. 
Secondly, as a consequence of that view, to discuss what com- 
parisons between the two generations are or are not possible. 
About nine years ago Pringsheim 1 formulated a hypothesis of the 
origin of alternation of generations. His views received, in one form 
or another, general acceptance. 
According to Pringsheim’s view the alternation of generations 
which is found in the Mosses, Ferns and Flowering-plants, can in its 
most rudimentary form be traced down into the Algae, in the genus 
Coleochaete , where alternation of generations was supposed to be just 
beginning. 
As so much turns upon the life-history of Coleochaete I shall go 
briefly over its main points. 
The Coleochaeie plant consists of a number of much-branched 
septate filaments, or in some (C. scutata) species of a flat plate of 
cells, and produces reproductive organs both sexual and asexual. 
The sexual process produces a fertilized ovum or oospore which 
1 Pringsheim, Ueber d. Generationswech. der Thallophyten, Jahrb. f. w. Bot., 
Bd. XI. 
[Annals of Botany, Vol. IV. No. XV, August 1890.] 
