ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
385 
A few drops of blood were placed on a slide in a 1 per cent, solution of 
formaldehyde and watched under the Microscope. The corpuscles, and 
especially the nuclei, were seen to swell rapidly ; the nuclei became as 
large almost as the original corpuscles, and were seen to pop out of the 
corpuscle like a grape from its skin. The envelopes then became very 
pale and finally disappeared from view, but the nuclei remained very 
distinct. Staining with Ehrlich-Biondi mixture showed that the body 
of the corpuscles had simply been rendered very transparent by the 
solution, while immersion in alcohol coagulated the fibrin into an opaque 
straw-yellow mass, and brought the corpuscle faintly back into view. 
This explains the phenomenon of the return of the colour of blood- 
vessels noted by Blum, and is due to the coagulation of the fibrin, which 
may also be stained somewhat by the colour drawn from the corpuscles. 
Mr. Kenyon concludes that it may be said, for general purposes, that 
solutions of at least more than 2 per cent, must be used in order to avoid 
the swelling and the decolorisation of specimens; solutions of from 
4 to 8 per cent, will give the best results. For histological purposes, 
formaldehyde combined with alcohol will give better results than either 
used alone. Weak (1 to 2 per cent.) solutions, by swelling nuclei, may 
serve the very important special purpose of demonstrating the presence 
of cells not otherwise readily distinguished. 
Preservation of Marine Animals.* — Mr. W. A. Bedenbaugh has 
applied the method of preservation suggested by T. Tullberg a few years 
ago, in which a novel use was made of magnesium sulphate. A method 
which was found successful with various marine animals was the fol- 
lowing : — The animal is killed by slowly adding a • 1 per cent, solution 
of chromic acid until the water contains from *03 to *05 per cent, of 
the acid. Sections of tentacles showed that the cells were not attacked 
by the substances employed. The author has found that the desired 
results may be obtained in a much simpler manner than that described 
by Tullberg. Complete stupefaction of the organism must be produced, 
so that when it is removed to a killing fluid no contraction takes place. 
The process, however, must not be carried on so slowly that maceration 
may ensue. For Coelenterates the most beautiful results were obtained 
with sea anemones, which ordinarily are so difficult to preserve in a 
well-expanded condition. They were allowed to expand in a dish with 
as little water as possible ; crystals of magnesium sulphate were then 
placed in the bottom of the dish and allowed to dissolve slowly until a 
saturated solution was obtained. A large Physalia treated in this way 
was preserved in 4 per cent, formalin with all the tentacles and polyps 
fully extended. For Echinoderms the method was found to be equally 
successful. Annelids, placed in a saturated solution of Epsom salts, 
became in a very short time perfectly limp, and were easily extended 
upon a glass plate, and treated with a fixing reagent. Balanoglossus , 
when taken soon after being collected, was thus preserved in nearly a 
perfect state. Good results were also obtained with Gephyreans and 
Nemerteans. For Ascidians it is best to add the saturated solution of 
sulphate intermittently with a pipette. A number of experiments were 
made upon Ctenophores, and successful results were obtained with the 
2 c 
1895 
* Amer. Natural., xxix. (1895) pp. 399-401. 
