NATURAL HISTORY MISCELLANY. 653 
anywhere for twenty or thirty years—at least the first time to 
give it a critical examination. The great rarity of the flower- 
ing of L. polyrrhiza is almost mysterious. Though I believe I have 
been enabled to throw some light on this matter, yet as I am not 
positive as to the correctness of my conclusions without further 
experiment, I refrain from printing them. — Henry GILLMAN, 
Detroit, Michigan. 
ZOOLOGY. 
AQUARIA Stupres.— At the outset of the present sketch we 
would premise that the glass side of our aquarium which is placed 
next to the wall, is never cleaned, and in consequence of this, it 
is soon covered over with a growth of what botanists call Con- 
ferve. The Confervee are among the lowest forms of Alge, a 
group which contains a great number of very minute microscopic 
plants, which have been, of late years, specially studied by micro- 
scopists. Among the lower forms of these Protophytes are the 
Diatomacez, Desmidiz and Volvocine, plants of very simple orga- 
nization, only lately removed from the animal kingdom. Other 
orders are the Palmellacez, likewise plants of humble type; Ul- 
vaceæ, plants of a rather more complex character ; Oscillatoriacez, 
remarkable for a peculiar kind of motion ; Nostochaceæ, Siphon- 
acez, and Confervaceæ. 
First let us scrape some of the growth off the glass at the back 
of the tank, then place it in the live box with a drop of water over 
it, and having adjusted our microscope, what do we see? 
First of all notice the vegetation contained in this drop of wa- 
ter. That long pointed ribbon, having the green colouring matter 
twisting and curling through the centre, is one of the Confervæ, 
a species of Spirogyra, and close beside it there is another jointed 
species having the chlorophyll or colouring matter in patches ; 
this is a variety of Stigeoclonium. These are purely vegetable, 
- and are the resort of many little creatures which revel and hide 
themselves among their tiny clusters of bands. 
The first intruder in the field of the microscope we would eall 
attention to is that shapeless mass near the centre. It looks like © 
a small piece of clear jelly with little black dots or granules 
within. But see, it has changed its shape: it is, as it were, running 
out; a finger-like process is flowing out here and there; the 
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