136 ALVALYN E. WOODWARD. 



to free it from serum, fresh fluid containing both serum and blood 

 cells, pieces of the alimentary tract, and mesentery. If a piece 

 of fresh mature testis be boiled in sea-water, in sea-water plus 

 sperm, or in distilled water, a purple compound is formed. This 

 color can also be obtained by treating the testis with strong 

 alcohol, which, as observed under the microscope, turns testis 

 cells from greenish brown to purplish. Whether or not this 

 would happen with immature testes could not be determined, 

 since the experiments were carried on during the breeding season. 



The sperm from one male, when examined under the micro- 

 scope, showed the presence of a few small pieces of testis, and, 

 when boiled, or treated with alcohol, turned purple. The testes 

 were then washed in running sea-water for about three hours, 

 during which they were occasionally pinched with forceps to 

 help free them from sperm. When this was apparently all washed 

 out, a portion of the testis was boiled in sea-water, without 

 giving a purple color. Treating with absolute alcohol, boiling in 

 distilled water, and boiling in sea-water plus fresh sperm also 

 failed to bring out any purple tinge from pieces of the washed 

 testes. The rest were then left standing over night in a finger- 

 bowl of sea-water. After twenty-four hours, it was observed 

 that they tinged the water slightly but distinctly purple. 



It seejns clear, then, that "purple x" arises from the fresh 

 testis, or from a reaction between testis and sperm. It still 

 remains to be learned whether or not it may be obtained from 

 the ovaries also. 



II. CHEMICAL NATURE OF "PURPLE X." 

 The best known pigment of sea-urchins is echinochrome, 

 whose chemical reactions are well established. It may be ob- 

 tained from the red blood cells by laking with distilled water, 

 by extracting with alcohol, chloroform or ether. The neutral 

 extracts are a cherry red, the addition of a small amount of NaOH 

 turns them yellowish, and acidulating with HC1 produces a red-" 

 yellow color (MacMunn, '85). 



Echinochrome was extracted from the washed blood clot 

 by laking with one volume of distilled water. An equal amount 

 of "double sea-water" (sea-water boiled down to one-half its 



