INCLUSIONS IN EGG OF ECHINARACHNIUS 471 



male of the same species or from one male Arbacia. In every 

 case three finger-bowls were kept. In one, kept as a control, were 

 placed eggs, 150 cc. of sea-water, and no sperm; in the second, 

 eggs fertihzed by species sperm, and in the third, eggs fertilized 

 by Arbacia sperm by the aid of alkah. A sample of unfertilized 

 eggs was preserved, and from the second and third finger-bowls 

 samples were preserved at varying intervals after insemination. 

 For example, series 4 was fixed every fifteen minutes, series 9 

 every twenty minutes, series 17 every ten minutes, etc. The 

 original bowls were kept until the following day and examined to 

 make sure that no contamination had occurred before actual 

 insemination, as proved by the failure in every case of the eggs in 

 the control to form fertihzation membranes or to cleave. In 



t±/ 



order to prevent chance fertihzation, hands, instruments, and 

 dishes were washed in fresh water before opening each animal. 

 In addition, the animal itself was rinsed in fresh water and then 

 in sterilized sea-water before being opened. Frequently all 

 dishes, pipettes, and instruments were put into a large kettle 

 and boiled. 



The fixing fluids used were picro-acetic (saturated aqueous 

 picric acid 95 parts, glacial acetic acid 5 parts), subhmate-acetic 

 (saturated aqueous corrosive subhmate 100 parts, glacial acetic 

 acid 5 parts), Bouin's fluid, Allen's warm modified Bouin (Bouin 

 50 cc. urea 1 gram, chromic acid 0.75 gram) made up immediately 

 before using, Perenyi's fluid, Meves' fluid (Lee, Vade-Mecum, 

 7th ed., p. 328), Champy's fluid (3 per cent potassium bichromate 

 7 parts, 1 per cent chromic acid 7 parts, 2 per cent osmic acid 

 4 parts), Cajal's fluids, Kelly's Zenker-formol, strong Flemming, 



