204 FISHERIES OF THE UNITED STATES. [20] 



about five minutes, to allow any fragments to settle to the bottom, then 

 pour the fluid, which should be quite milky, into another small beaker, 

 leaving behind, to be thrown away, any particles which may have set- 

 tled 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 eggs 

 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 watch 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 insure the speedy 

 contact of each of them with some of the male cells. 



"Fill the crystal with water again, and stir and pour off, 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 they form a 

 very thick layer, only those which lie near the surface have room to 

 develop. 



"-The beaker should now be allowed to stand for about ten minutes, 

 and in the mean time some of the eggs may be picked out with a (lip- 

 ping-tube, for examination under the microscope. In using the dipping- 

 tube, cover the large end with the tip of the finger, and run the small 

 end down close to the bottom of the beaker, and then take the finger 

 off the top, and as the water runs in at the bottom it will carry some of 

 the eggs with it. When the tube is filled, place the finger on the top 

 again, and draw it out of the water, and, holding it perpendicularly 

 on the center of a glass slide, and taking the finger off the top, allow a 

 good-sized drop to run out into the slide. 



"If things are working properly, each egg should now have a number 

 of male cells attached by their heads to its outer surface, with their 

 tails radiating from it in all directions, as shown in Fig. 51. 



"It is not necessary that more than one male cell should fasten on to 

 each egg, but they usually cover them in such numbers that the lash- 

 ing of their tails causes the eggs to rotate and move through the water. 



"As soon as all the eggs have male cells attached to them, it is neces- 

 sary to get rid of the superfluous male fluid, for it would soon decay 

 and pollute the water if it were allowed to remain, and if it is not drawn 

 off from the eggs while they are at the bottom, it is almost impossible 



