
B WHAT IS A DESMID? 




















reason alone, there seems to be good grounds for supposing 
that it has been very aptly applied, for naturalists are 
strongly of opinion that the first forms of vegetable life 
which made their appearance upon the surface of the globe 
belonged to this group, and we see them at the present day 
occurring as the harbingers of more complex plants in pools 
and ponds, on rocks and by road-sides. The amount of 
study that has been bestowed upon the Desmids is really 
very great, but it has been by a special class of observers 
who have been in the habit of not trusting to the revelations 
of their unassisted eyes, but have called in the aid of all the 
contrivances of modern mechanical skill as embodied in that 
perfect instrument of research, the achromatic microscope. 
By such students we are assured that in no respect do they 
really approach the animal kingdom. Many arguments, it 
is true, have been from time to time advanced in support of 
their animal affinities, but these have all been determined, 
now that their life history and that of many other undoubted 
and undisputed plants have been better understood, to be 
but strongly indicative of their vegetable nature. But the 
very fact that for a long time they continued to be bandied 
from one kingdom to the other, now plants and then animals, 
only to become plants again, indicates the difficulties atom 
dant upon their study, and the uncertain tenure with which - 
they, even now, hold the position they by courtesy are per - 
mitted to occupy. | f 
Ehrenberg, the great German microscopist, asserted that 
one of the Desmids, known by the name of Closterium, pos 
sesses true organs of motion, which it protrudes through 
apertures in its extremities, and keeps in continual action: 
. Unfortunately, however, more recent investigation has T°- 
vealed the fact that this statement is wanting in accuracy: - 
No such organs of propulsion are to be seen now that Wè - 
mre possessed of much better microscopes than the Prus- - 
sian hilosopher was wont to use, therefore we can but | 
e the “feet” of his Closterium to defective methods 









