190 
NOTES AND MEMORANDA. 
solution on the preparation, and at the very moment of the cataclysm 
all the living beings, animal and vegetable, are instantaneously ren- 
dered immovable. I then expose the preparation to a current of air, 
which takes off the disagreeable vapours of the acid and evaporates 
the greater part of the water. 
I have treated in this manner some filaments of Vaucheria collected 
in March last, and I found that they preserved their form and colour — 
the protoplasm was not retracted, and they were in fructification. The 
antheridia and the oogonia were visible with a tint of green much 
deeper than the rest of the filaments, and containing globules of fatty 
matter, which the acid had coloured brown or black. The ribbons of 
the Diatomacea), Himantidium pectinale, the zigzags of Diatoma vidgare 
preserved their natural asjDect and tint, the isolated Naviculw fioated 
in the preparation with some Cosmarium and Closterium of a green 
as bright as if they had never been subjected to the action of any 
reagent, but the motile corpuscles of these DesmidiEe were for ever 
arrested. Here and there were some Infusoria [Paramecia, Stylonichia), 
&c., of a light brown colour — immovable with all their cilia arrested ; 
an Euglcna viridis of a brilliant green showed its red ocular point and 
its long flagellum, — all these beings, in a word, seemed still living, 
and their protoplasm had not changed in form. In the diatoms 
some globules of a light brown indicated their oily nature, but 
no other modification appeared to have been produced. 
The contractile animalcules were found in all positions. Certain 
Vorticellffi were immobilized in a complete state of extension, and 
their peduncle had lost its elasticity. The cuticle ordinarily re- 
mained uncoloured, but the internal parts and the muscle of the peduncle 
were brown. The rotifers were in all attitudes ; some completely 
developed, the wheels exposed and bordered with cilia, which could 
often be counted. I have counted twenty on the wheel of a Pliilodina 
erytlirophtlialma, of which the ocular points, oblique and elongated, 
like the eyes of a Chinese, remained red. It can easily be established 
thus that the rings of their bodies, articulated like a telescope, are 
much less variable than they are ordinarily said to bo. 
In short, all the living animals were immobilized in the position 
which they occupied at the moment that the acid touched them. 
The preparations thus obtained can be preserved — by passing 
over them some glycerine the diatoms, desmids, rotifers, and infusoria 
do not contract, and the preparation can be sealed down. In the 
Conferva? and the other filamentous alg£e, however, the protoplasm is 
subjected by the glycerine to a very notable shrinking. It is pre- 
ferable, therefore, to preserve the preparations in a 1 per cent, 
solution of carbolic acid. 
Finally, I should mention that the reagents ordinarily used in 
histology, and particularly the colouring matters, may be applied to 
the animalcules. I will give in another paper the very interesting 
results obtained by these methods, but I should say now that in con- 
sequence of the strong action of the osmic acid on the animals (giving 
them a brownish tint), they colour badly or confusedly by the gene- 
rality of colouring matters. The method which I have hitherto found 
