THE BIOLOGY OF THE CELL SURFACE 



But I went farther in insuring the viability of the eggs. 

 I used dilutions of a degree which allowed the eggs to fer- 

 tilize and develop whilst in the dilution. Naturally, this 

 development in the more dilute sea-water is far from normal. 

 Nevertheless, if fertilization and development proceed in a 

 solution, that solution is not as destructive as one in which 

 both egg and spermatozoon are killed. The table appended 

 gives figures to show the per cent, of development of eggs 

 fertilized in hypotonic sea-water of various grades in which 

 they develop. 



Table II. — Per Cent, of Cleavage and of Swimming Forms of Eggs 



Fertilized in Various Dilutions of Sea-water, in Which They 



Remain During Development* 



* This table represents one experiment of 10 made for each dilution. In most of the 60 experiments 

 the controls showed 100 per cent, cleavage and more than 90 per cent, normal trochophores. 



I spent a great deal of time in taking these precautions 

 because I wished very clearly to establish that the eggs in 

 which I observed drops of water were living cells capable of 

 normal processes. Many times indeed I fertilized eggs 

 immediately upon their return to normal sea-water — that 

 is, during the process of their return to normal condition 

 it was possible to initiate development in them; hence the 

 drop-formation did not interfere with fertilization. Thus, 

 these observations were made on viable cells; I can think 

 of no source of error left unguarded. 



Now let us follow the process in detail.^ In the hypotonic 



^ Although incidental observations had often been made earlier, 

 the first systematic ones were 7nade in ig2^ on which the initial 

 report published the next year zvas based. 



130 



