FERTILIZATION AFTER INITIATION OF DEVELOPMENT. 269 



had cleaved but the cleavage count is as nearly correct as very 

 careful examination could make it. The larvae appearing in 

 dish A i, after insemination, were a good lot: approximately 

 70 per cent, swam at the top of the water and more than 50 per 

 cent, are entirely normal. Compared with the swimming forms 

 of A 5, obtained after fertilization, there is a great difference: 

 only a small percentage of the eggs subjected to the hypertonic 

 solution for one hour (A 5) and inseminated immediately, gave 

 rise to swimming larvae; and of these only a few could be seen 

 swimming at the top of the water. Almost any form of moving 

 masses of protoplasm may be found among the forms of this 

 dish from a very few apparently normal forms to masses that 

 gave only the least bit of quivering movements; blunt masses, 

 angular forms possessing no semblance of morphological simi- 

 larity to a normal form, dumb-bell shapes one half of which 

 swims and pulls the other lifeless half around with it, bits of 

 spinning protoplasm that appear somewhat as half, quarter or 

 eighth blastulae are to be found abundantly. As the length of 

 exposure to hypertonic solution is increased before insemination 

 one encounters a more and more abnormal lot of larvae; there 

 is not only an increase in the degree of abnormality but the 

 percentage of swimmers 'is gradually reduced until dish An 

 (inseminated) contained only 10 per cent, of eggs that gave the 

 least signs of life, and of these not any swam at the surface of 

 the water; A 12 (inseminated) revealed not a single form that 

 approached the normal. 



It is well to point out again the inability of one to obtain an 

 absolutely correct larval count, for among the eggs that have 

 not been fertilized are many that have undergone cytolysis ; 

 the count is only relatively correct but it will be sufficient to 

 illustrate the decrease of the capacity for fertilization of eggs 

 that have been exposed to the activating influence of the weaker 

 solution of hypertonic sea-water. 



When the more concentrated solution is used as an activator 

 and is followed by insemination, a different condition is en- 

 countered. After the hypertonic treatment alone, of say thirty 

 minutes, one obtains a much larger percentage of cleavage 

 and a decidedly higher percentage of swimming larvae than is 



