OF WASHINGTON. 101 
become detached from the body of the ant, showing that the egg had been 
deposited in the living host. Hoping to be able to clear this subject up 
more fully at some future time, I must leave it as it stands for the present.* 
Mr. Lugger read the following paper : 
A NEW METHOD OF PRESERVING TRANSPARENT AqyATic INSECTS 
FOR THE MICROSCOPE. 
BY O. LUGGEK. 
The study of transparent aquatic larvae of the various orders of insects is 
both amusing and instructive. For the former purpose a common life-cell 
is all that is required, and many a pleasant hour can be spent with the 
microscope in contemplating the beauties of these delicate objects. The 
whole of the internal anatomy and the workings of the various organs can 
be studied with ease. But for the more serious work the life-cell alone is 
not sufficient. The object to be studied will soon die under these unnatu- 
ral conditions for lack of air, and it is often difficult, if not impossible, to 
substitute a second specimen for the dead and now opaque object. Even 
if careful drawings have been prepared of the still transparent larva, it is 
all-important to preserve the object in such a manner that it can always 
be consulted at any future time. 
Various, more or less successful, methods have been invented, but all 
have proven futile after a short time; the preserved specimens either 
shrink out of all proportions or they become opaque and useless. 
Some time ago I received by exchange a slide prepared by Mr. Dunker, 
of Berlin. He succeeded in inventing a method of preparing the lower 
animals and plants found in standing water in a perfectly natural condi- 
tion. Infusoria, small Algae, Rhizopods, Flagellates, Ciliates, Chloro- 
phyllacese, Desmids, Diatoms, Daphnia, and Cyclops species were thus 
prepared by him and sold in large numbers. However, Mr. Dunker has 
shown very little liberality in this matter, and keeps his method a secret. 
When I received the slide I concluded to sacrifice it, hoping to be able to 
discover his method. I broke the cover-glass, and immediately I per- 
ceived the odor of something familiar, and related to the cheap alcohol 
made of wood. The substance is Rectified Wood-vinegar (Acetum pyro- 
lignosum rectificatum). Many experiments during the last three months 
convinced me that this is the preserving material long desired. Of course, 
I do not know whether Mr. Dunker uses the same simple material or a com- 
pound in which it occurs. 
A neat and very useful cell for mounting aquatic specimens was shown 
* Mr. Howard, in a paper read before the Biological Society of Washing- 
ton, October 22, 1887, stated that this parasitic, larva probably belongs to 
the Dipterous family Conopidcz, the larvse of one or more species of which 
have been found in Europe to be parasitic in the abdomen of Bombus, 
Ostnia, Odynerus, and Pompilus. 
