"° THE BIOLOGY OF THE ANIMAL 



ferent directions, in order that the inland student may 

 see even in the preserved specimens the wonderful flex- 

 ibihty of the body and rays of the starfish. Care must 

 be taken not to put too many specimens into the vessel 

 of alcohol, for the water in the body-cavity and tissues 

 of each animal weakens the alcohol a certain amount. 

 With ninety per cent, alcohol the bulk of the specimens 

 should be not more than one-third of the bulk of the 

 alcohol used. After the specimens have lain in strong 

 alcohol for an hour or two, insert the needle of a hypo- 

 dermic syringe into the roof of each ray, near the tip, and 

 fill the cavity of the ray Avith alcohol. This preserves 

 the internal organs in good condition, keeps the ray 

 distended in its natural shape, and the hole made by the 

 needle does not interfere with dissection ; besides, the 

 hole, being very small, becomes plugged up immediately 

 after the withdrawal of the needle, and thus the alcohol 

 is kept from oozing out, as it would through a larger 

 opening. After being in the strong alcohol for two or 

 three days, the specimens may be kept indefinitely in 

 seventy per cent, to ninety-five per cent, alcohol. For 

 the study of the hard parts alone, however, it is well 

 to use dried specimens. These are prepared by taking 

 some of the alcoholic specimens treated as above, and 

 laying them for a day or two in the hot sun or in an oven. 

 If dried in the open air, they should not be left out of 

 doors overnight nor allowed to become damp. For the 

 study of the structure and arrangement of the individ- 

 ual portions of the skeleton alcoholic or dried specimens 

 may be soaked for a few days in a ten per cent, solution 

 of potash. As soon as the soft parts commence to mace- 

 rate, the specimens may be carefully brushed with a 

 ragged tooth-brush in order to remove the skin and 

 flesh. If soaked too long, the skeleton will drop to 



