280 APPENDIX. 



In collecting, it is not enough to tear away the top of the sponge : 

 gemmules are most abundant in its deepest parts. A sharp hatchet, 

 with which a chip bearing the entire sponge may be detached from 

 submerged timbers, will therefore be found very serviceable. A broad, 

 dull knife blade may be used for detaching such as grow on large 

 stones. Specimens will be gathered most quickly by wading with 

 high boots in shallow water, and cutting them free from chunks and 

 stones which lie on the bottom. They will be collected most easily 

 when found growing upon partly submerged boughs of trees, which 

 may be drawn out of the water. 



Specimens may be preserved in alcohol. The skeletal framework 

 will be readily preserved by drying the specimens in situations 

 sheltered from the direct rays of the sun. 



IV. On preparing Gemmules and Spicules for Examination. Dissect 

 out with needles half a dozen gemmules from the sarcode or from 

 the dried sponge mass. Place them together on the center of a clean 

 glass slip, and cover them with a drop of boiling nitric acid. After 

 five minutes (more or less, as may prove necessary time for rendering 

 their outer coat transparent without destroying it) wash off the acid 

 by running successive drops of water across the slide while holding it 

 in an inclined position. Then cut two or three of the gemmules in 

 halves or in quarters, so as to expose the edges of their outer coat. 

 Then remove the water, as much as possible with blotting paper, 

 and the remainder by adding strong alcohol. Renew the alcohol 

 once or twice ; then remove it with blotting paper, and cover the 

 gemmules with a drop of turpentine or benzole. After allowing 

 a few moments for the gemmules to become penetrated with the oil, 

 remove excess of it with blotting paper, and add a drop of balsam and 

 a cover glass, and the preparation will be properly and permanently 

 made. 



Place bits of the sponge containing skeletal spicules, and several 

 gemmules, together in a small test tube, and boil them for several 

 minutes in a few drops of nitric acid : the spicules will alone remain 

 undissolved. Fill up the test tube with water, heat gently, and set 

 aside. The spicules will settle to the bottom. After they have set- 

 tled, hold the test tube slightly inclined, and roll it slowly between the 

 fingers to collect the spicules to one spot on the bottom. Holding one 

 end of a small glass tube closed with the finger, push the open end 

 down inside the test tube to this spot, and then lift the finger at the 

 top sufficiently to admit a drop of water at the bottom. This drop 

 will carry into the tube a load of spicules, which may be transferred 

 to the center of a clean slip. After the water has evaporated, and left 



