STAEFISH 99 



pieces. When thoroughly cleaned, rinse the skeleton in 

 fresh water and put it into strong alcohol for four or 

 five hours, then dry in the open air or over a stove. 



For the study of the water-vascular system, injected 

 specimens should be prepared. A very convenient 

 method is to kill the starfish in fresh water; after the 

 animal is dead warm the water up to the melting-point 

 of gelatin, cut off the tip of one of the rays, insert the 

 tip of a fine-pointed syringe into the end of the radial 

 water-tube, and with a slow but firm pressure fill the 

 water-vascular system with a carmine or Prussian-blue 

 injecting mass. Specimens thus prepared may then 

 be hardened in alcohol, where they will keep indefi- 

 nitely. 



For the microscopical examination of cross-sections of 

 the rays and disk, small specimens one-half inch to an 

 inch in width should be provided. They may be found 

 on rock- weed, eel-grass, the surface of the mud, etc., in 

 quiet pools along the sea-shore during the summer 

 months. They should be quickly picked off the surface 

 to which they are adhering and instantly dropped into 

 strong alcohol (ninety-five per cent, to one hundred per 

 cent.) and left for four to six hours. The alcohol causes 

 instant death, and the ambulacral feet and tentacles re- 

 main expanded. The specimens may then be placed in 

 one -half per cent, to one per cent, chromic acid for 

 about twenty-four hours, or at least until no more bub- 

 bles arise, showing that the acid has dissolved all or 

 nearly all of the calcareoiis part of the body, and left it 

 in condition to be cut with a sharp knife. The starfish 

 is then placed in seventy -five per cent, alcohol for a 

 day, then into ninety per cent, for another day or until 

 wanted for examination. Specimens may be embedded 

 in paraffin, or in celloidin, and cut on the microtome. 



