ARTIFICIAL PARTHENOGENESIS IN ARBACIA. 151 



SUMMARY. 



1. The conditions governing the production of artificial 

 parthenogenesis in Arbacia by the use of sea-water concentrated 

 by evaporation to a definite volume, are purity of solutions, stage 

 in development of ovarian eggs, duration in concentrated solu- 

 tion, temperature of solutions. 



2. The efficacy of solutions is subject to the presence of for- 

 eign substances, spermatozoa, relative number of eggs in a given 

 amount of concentrated sea-water, and temperature. Foreign 

 substances are excluded through extreme care in the preparation 

 of solutions ; spermatozoa are eliminated by raising normal sea- 

 water to 70 degrees, by sterilizing all instruments in the flame, 

 by washing thoroughly the body of the sea-urchin and the hands 

 of the operator for three brief periods under stream from the hy- 

 drant. Results are most constant at normal temperature of sea- 

 water. Development is obtained at room temperatures 22 to 

 24. Variations in temperature of solutions materially affect the 

 development of the culture. 



3. The concentrated solution appears to be effective in pro- 

 ducing development in oocytes only. By reason of the opacity 

 of the egg it is difficult to ascertain the exact stage or subsequent 

 behavior in concentrated solution. 



4. The average optimum period for eggs in concentrated solu- 

 tion lies between one hour and fifty-five minutes and two hours 

 and five minutes. 







UNIVERSITY OF KANSAS, 

 April 4, 1903. 



