24 BASIC METHODS FOR EXPERIMENTS 



card the perivisceral fluid. Next, either place it in a clean 

 Syracuse watch-glass so that the eggs exude through the genital 

 pores, or carefully remove the ovaries to 250 cc. of sea-water 

 into Avhich the eggs will fall freely from the ovaries. In the 

 latter case, strain the eggs free from debris by putting them 

 through cheese-cloth, previously soaked in running sea-water 

 after having been washed in fresh water. 



If necessary, wash the eggs four times by decanting the sea- 

 water above them as soon as they have settled, adding very 

 gently sea-water in an amount equal to that removed. Again 

 the washing should not take more than one hour. After each 

 washing, test the eggs by trial insemination on samples. If 

 after the fourth washing the trial insemination does not yield 

 close to 100 per cent fertilization, discard these eggs and use the 

 eggs from another female that yield practically 100 per cent 

 fertilization. 



I find it worth while to open several females, selecting the 

 eggs from the best. I never mix the eggs from several females. 

 One point the worker must remember: Arhacia eggs are not 

 "C. P." chemicals that give the same results day in, day out. 

 Too many variables enter: the time in the breeding season, the 

 freshness and vigor of the animals — which depend upon the 

 length of time they have been in the live cars, after having been 

 collected — the fullness of the gonads — which depends to a great 

 extent upon the collecting grounds from which the animals come 

 during a given lunar period — the abundance of the "blood 

 inhibitor" present, temperature, etc. 



In passing, I may note that I also use Echinarachnius to feed 

 Arhacia, thus restoring the sea-urchins previously in poor condi- 

 tion to a high degree of excellence. 



Echinarachnius 



The egg of Echinarachnius is one of the most beautiful in the 

 Woods Hole region. It is larger than that of Arhacia and 

 possesses less pigment. En masse, the eggs are of a red hue 

 because of the pigmented jelly hulls that enclose them; when this 

 jelly is removed, they are a pale yellow — lighter than an equal 

 mass of Asterias eggs. Their color is due to chromatophores 



