88 The American Naturalist. [January, 
Plant structures are more or less well preserved ; most fruits keep 
well. 
Chlorophyll is not extracted, but after a long action of the fluid del- 
icate leaves may be changed. The duration of the retention of other 
coloring matters is different with individual plants. 
Microscopic sections of plants that have been a long time in formol 
give fine preparations. 
Dilute formol is not combustible and is much cheaper than alcohol. 
To the above experiments described by Blum may be added those 
of Dr. Th. Pintner, Dr. C. Krückmann, and a few notes of my own. 
Dr. Pintner used a 1 per cent. solution of formaldehyde iu sea water. 
for Discomedusæ, Æquorea and Aurelia without their form being 
affected.” The same solution was used with sponges such as Suberites 
dominicula and massa, Clathria coralloides, Aplysina aérophobia, ete., 
with equally good results. But animals that contract much in killing 
must first be treated with Lo Bianco’s Naples methods, and then trans- 
ferred to the solution of formaldehyde. He found that all animals do 
not retain their color, as for instance, the red coloring matter of acti- 
nia and of Comatula is extracted. 
Dr. Kriickmann working with bacteria used stronger solutions and 
obtained the best results by combining corrosive sublimate with forma- 
lin” To begin with, a formalin solution of moderate strength was 
used and this gradually increased until the specimens were in pure 
formalin. Bacterial cultures were fixed by placing them in an excic- 
eator containing formalin instead of sulphuric acid, and in order to 
tan the surface of the medium, it was covered with a 1:10 solution of 
formalin containing 1 per cent of sublimate. This was later changed 
to astronger solution of formalin and the tube hermetically sealed. 
By following this process he found that colors were much better pre- 
served and the more or less inevitable crumpling very much dimin- 
ished. The solution worked well with all media except potato. 
The few experiments that have been performed by myself seem to 
indicate that too weak solutions of formalin have hitherto been used 
except in the bacterial experiments of Kriickmann. The material 
used was what came nearest to hand, and consisted of a tree-frog, sala- 
manders, earth worms, sow-bugs, myriapods, plant-lice, slugs, cat liver 
and blood, blood of salamander, nostoc and a pond scum. The solu- 
tions used varied from ł per cent. to pure formalin. Two species of 
8 Ver. zool. bot. Ges. Wien, xliv, (1894), p 
? Centralbl. f. Bakteriol. u, Parasiteuk., aS ab pp. 851-7. 
