l66 Charles R. Stockard 



Institute of Poughkeepsie, N. Y. I wish to express my thanks to 

 this Institution, as well as to the authorities of the Marine Biolog- 

 ical Laboratory, for the working facilities furnished me while 

 there. I am also glad to express my indebtedness to Prof. T. H. 

 Morgan for many helpful suggestions, and to Prof. A. P. Mathews 

 for assisting me in calculating the osmotic pressures of my solu- 

 tions. 



METHOD AND MATERIAL 



As Stated above the eggs of Fundulus heteroclitus lend them- 

 selves peculiarly to such investigations as this. They are hardy 

 and develop in different strengths of almost any solution applied. 

 The action of a salt in sea-water solutions is generally more or 

 less modified, owing to the presence of the salt constituents of the 

 sea-water itself, but this effect can be controlled by the use of the 

 distilled water solutions. 



The spawning season of this fish begins at Wood's Hole about 

 the middle of June and extends well into the first part of August, 

 thus giving an opportunity to repeat the experiments many times 

 and to test any uncertain points which might arise. In fertilizing 

 the eggs I have found it advantageous to strip them from the 

 female directly into a dry bowl and then apply the milt from the 

 male, stirring the eggs well so as to mix them thoroughly with the 

 milt. They are left to stand for five or ten minutes when water is 

 added. This method insures a larger percentage of fertilized eggs 

 than will result if they are under waterwhen the spermatozoa are 

 applied. In those cases where the eggs were to be treated with 

 solutions of salts in distilled water they were placed, after being 

 fertilized "dry" directly in fresh water, thus little if any salts 

 could have reached the eggs after they had been removed from 

 the body of the fish. 



The time elapsing between fertilization and hatching varies con- 

 siderably with the temperature, season, etc., being from about 

 eleven to eighteen days. 



The salts used in these experiments were with few exceptions 

 fresh Kahlbaum preparations. High percentage solutions were 

 prepared and these were diluted to the proper strengths from time 



