22 JOURNAL OF SCIENCE. 
animals, such as the oceanic hydrozoa which are occzsionally 
found on these coasts, and which do not readily bear transport. 
By far the majority of specimens may, however, be taken 
home in vessels of sea-water. The water should be changed 
occasionally during the day, and always immediately before 
leaving the shore. It is advisable, whenever practicable, to take 
a separate vessel of sea-water, and to renew that in the collecting 
bottles immediately on reaching home. 
A similar procedure will of course answer for fresh-water 
collecting. For terrestrial forms, match-boxes, &c., may con- 
veniently take the place of bottles. A very good collector’s 
companion for ordinary walks is a common waterproof sponge- 
bag, which answers admirably for either marine, fresh-water, or 
land organisms. 
The work of preservation should be begun as soon as possible 
after reaching home; a night’s sojourn in the collecting vessels 
will cause the death of many of the more important specimens. 
The following hints for preservation of various invertebrata 
are founded partly on my own experiments, partly on notes 
furnished to me by Prof. Haddon, of Dublin, of the methods 
used at the Zoological Station at Naples :— 
SPONGES.—For ordinary purposes, place at once in al- 
cohol. For the preparation of microscopic specimens showing 
the constituent cells, take a small piece of the sponge, not larger 
than the end of one’s finger, and place it in a small vessel (e.¢., 
a wine-glass), containing just enough sea-water to cover the 
specimen. Add a few drops of osmic acid, cover the vessel, and 
allow it to stand zz a dark place for 24 hours, then rinse with a 
little alcohol to get rid of the acid, and place in alcohol for 
permanent preservation. 
HyDROID PoLyps (Sertularians and Campanularians).— 
Ascertain by examination with a low power that the specimen is 
actually living and has expanded polypites. Transfer quickly 
from the sea-water to pot. bichrom. solution: this kills the poly- 
pites in an extended condition. Keep in the bichromate for 24 
hours, then transfer to alcohol 50 p.c. for 24 hours, then to 
alcohol 75 p.c. for the same time, and finally to strong alcohol. 
By this treatment with alcohol of gradually increasing strength, 
shrinkage is greatly diminished, the specimen being at the same 
time thoroughly hardened. 
Instead of the bichromate, the polypites may be allowed to ex- 
pand in a small quantity of sea water and a little boiling water 
added to kill them ; then place in picric acid solution for 2 or 3 
hours, and finally treat withalcohol as above(Huxley and Martin). 
In both cases the alcohol should be changed until it is no 
longer discoloured by the bichromate or picric acid. 
MEDUS&, SIPHONOHORA (Portuguese Man-of-War, &c.), AND 
CTENOPHORA.—Place eitherin potassium bichromate for 24 hours, 
or in chromic or picric acid for 2 or 3 hours; or place in the 
smallest possible quantity of sea water, and add a few drops of 
osmic acid. This latter plan produces the most beautiful speci- 
