316 HANDBOOK OF INVERTEBRATE ZOOLOGY. 



and poured into the beaker. Stir the contents of the 

 beaker for a short time, and then allow it to stand about 

 five minutes, to allow any fragments to settle to the bot- 

 tom, then pour the fluid, which should be quite milky, 

 into another small beaker, leaving behind, to be thrown 

 away, any particles which may have settled to the bottom. 

 The male cells retain their full vitality for several hours 

 after they have been mixed with sea-water, so the beaker 

 may be set aside to wait until the eggs are ready. The 

 eggs swell up and break to pieces within a very few 

 minutes after they are mixed with water, unless they are 

 fertilized at once, so it is much better to add the egfors to 

 a previously prepared mixture of male cells and water than 

 it is to put the eggs into the water to wait until the male 

 fluid is got ready. 



Taking now one of the females, remove and chop up the 

 ovary in the same way in another watch-crystal, observing 

 the same precautions in removing all portions of the body. 

 Fill the w^atch-glass with water, and stir and pour off into 

 the beaker as before, giving the contents of the beaker a 

 good stirring after each lot of eggs is added, in order to 

 diffuse them through the water at once, and thus ensure 

 the speedy contact of each of them with some of the 

 male cells. 



Fill the crystal with water again, and stir and pour ofi", 

 and repeat until all the eggs have been washed out of the 

 fragments of the ovary. 



Another female may now be cut up, and the eggs may 

 be added to the contents of the same beaker, but if the 

 females are large, and yield many eggs, it is not best to 

 use more than one, for although there are enough male 

 cells to fertilize a very great number of eggs, the eggs are 

 heavier than water and soon sink to the bottom, and if 



