4 
CHLOROSPERMEJE. 
unicellular Algae of Braun are the male organs or androspores of other Algae. I think 
it can hardly he questioned that multitudes of the Palmelloid for ms are either spores or 
imperfectly developed fronds ; and the same is probable of many Confervoids. As yet 
the subject, except in a few able hands, has been confused rather than rendered more 
clear by the labour bestowed by authors upon it. There has been too great an anxiety 
to establish new genera and species, without due regard being had to circumstances of 
growth and development ; and the unfortunate student who now attempts' to study 
the fresh water Algae is oppressed by an accumulating mass of bad species and genera, 
which all have to be in some degree mastered before he can make dean work. Add 
to this, that in the present state of our knowledge it is absolutely necessary, in most 
instances, to have the living plant at hand, and it will be understood what a difficult 
task it must be to give a good account of the Chlorospermatous series of the Algae. 
No one can be more sensible than I am myself of the very imperfect nature of the 
sketch attempted in the present memoir. I write at a distance from my subject, and 
have rarely had more than dried specimens to examine. Though many of them were 
personally collected by myself in 1850, when travelling in America, on very few have 1 
preserved notes taken from the recent plant. This is perhaps of less account among 
the marine kinds, which formed the staple of my personal collections, for the marine 
species recover their characters on re-immersion much more perfectly than the fresh 
water kinds. But the want of living specimens has seriously barred my attempts to 
describe the fresh water species, with the exception of such easily preserved kinds as 
Hydrodictyon , Batradiospermum , Lemanea , Petalonema , &c. The Zygnemaceae, of 
which I have received several, and which are probably numerous in America, so com- 
pletely lose their distinctive characters in drying, that I have been forced to omit them 
altogether. So also it has happened with the species of. Oscillatoria , and of the Con- 
fervoid Algae generally. I must therefore leave the task of describing the fresh water 
Algae of America to other hands ; to some one living among them, and having eyes 
fully open to the difficulties of his task, and zeal and ability to work it faithfully. And 
here I cannot omit a slight tribute to the memory of one in whom were combined in 
no common degree the qualifications which make an able naturalist, and who, had he 
lived, would probably have taken up the broken thread. 
I allude to the late Professor J. W. Bailey of Westpoint, one of the earliest explorers 
of American Algae, and whose very able memoirs on the Diatomacece have won for him 
an imperishable name in the annals of science. To me his loss is more personal than 
to most of his botanical friends, for from the hour we first met there grew up between 
us a warm friendship which death has interrupted, but which I trust it has not ended. 
He it was who first suggested to me a Memoir on the American Algae ; he arranged 
with the Smithsonian Institute the terms of its publication ; he supplied me with a 
multitude of specimens ; and to his influence I owe the assistance I have received from 
many American algologists who looked up to him for direction in their studies. He 
was, as far as the Algae are concerned, my chief American referee, to whom I could 
apply when seeking information on local matters, connected with this branch of study. 
With him I constantly associated my work, and to his approbation 1 looked forward as 
