314 HANDBOOK OF INVERTEBRATE ZOOLOGY. 



stances this power should also show the " tails," as very 

 faint undulating lines. 



If the " heads " vary much in size, or if they are aggre- 

 gated into bunches, with the "tails" radiating from the 

 bunches in all directions, or if there is much granular mat- 

 ter so small that the outlines of the particles are not visible 

 when magnified five hundred diameters, 

 the fluid is not perfectly ripe^ and fertihza- 

 tion with it will not, in all probability, be 

 very successful. 



Fig. 158. — A portion of Fig. 157 magnified five 

 Fig. 158. hundred diameters. 



As the male cells are infinitely more numerous than the 

 eggs, the ripe fluid from even one small male is enough to 

 fertilize all the eQ-o^s of five or six laro^e females. 



In order to fertilize the eggs, all that is necessary is the 

 mixture of the ripe eggs with a little of the ripe male fluid 

 in a drop of water. If the point of a knife-l)lade be 

 dipped in the fluid from a female and touched to a glass 

 slide, and then dipped into the fluid of a male and touched 

 to the same part of thfe slide, and a drop of sea-water be 

 added, to cause the two to meet, most of the eggs will be 

 fertilized, and their early stages of development can be 

 studied in a single drop of water, but to secure the fertili- 

 zation and healthy development of great numbers of eggs, 

 several precautions must be observed, and a few instru- 

 ments and pieces of apparatus are needed. 



The following is a list of the things needed for procur- 

 ing, fertilizing and hatching the eggs : A pair of sharp- 

 pointed scissors ; a pair of small forceps ; half a dozen 

 watch-crystals ; a set of about half a dozen glass beakers, 

 or tumblers, of different sizes, from half a pint up to half 



