24 Notes on some Microscopic Organisms. 
way, and I feel sure that it is only by such earnest application 
that we can acquire any knowledge of the phenomena peculiar to 
what we know as life which will be of any lasting value. 
The plant I examined belonged to the genus OEdogonium, of 
Link. The particular species was undetermined, and when it is 
considered upon what slight and evidently artificial characters 
species have been founded among the Cryptogamia, I am sure that 
I will be excused from venturing upon such delicate ground, 
especially as by so doing I run no danger of offending those who 
do not recognize the existence of species at all, or, on the other 
hand, puzzling those who do recognize the existence of natural 
species, but are not anxious to have them multiplied. The form 
observed is extremely common, growing in clear springs in various 
sections of the country, and is especially plentiful around the city 
of New York. To the unaided eye it appears as a bunch of fine 
filaments of a light green colour, and by the unknowing collector 
of microscopic wonders is usually classed under the inclusive title 
of “ Confervas.” My first investigations were made in the month 
of April, a season when this peculiar phase of this plant appears to 
be common. And here I would impress upon students of nature, 
and more especially those who use the microscope to assist them in 
their investigations, the great advantage to be derived from making 
collections early in the spring. At that time the young stage of 
many organisms may be procured, and, as that season is also the 
time of rapid change and development, we are placed in the very 
best condition for watching transformations that may take place, 
and determining the true position of many forms which might be, 
and in many cases, I am convinced, have been ranked as perfect 
species. Let the young biologist remember that our knowledge of 
a species is never complete until we have made ourselves acquainted 
with the whole cycle of its existence from the germ to the adult, 
from the parent to the offspring ; and the early spring in such 
latitudes as have a severe winter, diming which almost all life lies 
dormant, is the time for such studies. 
Up to this time the amount of knowledge bearing the portion 
of the life-history of the germs OEdogonium of which I desire to 
treat, is very incomplete ; there being gaps which I think it will 
be found that what I have seen and have to describe, just fit into 
and fill. The perfect plant itself consists of an extremely fine, 
green-coloured filament, cylindrical in form, and having its frond 
divided at regular intervals by partition walls, so that the indivi- 
dual plant may be represented by a series of tubular cells or boxes, 
like tall pill-boxes, united end to end. The enclosing wall of these 
cells is itself colourless, and it would be difficult to see it, did it not 
possess a different refractive power upon light to the water in which 
it floats. It probably consists essentially of the same substance, 
