128 



FRANCIS MARSH BALDWIN. 



tively easy matter to approximate the most suitable concen- 

 tration of each alcohol after the first had been determined. 



AMYL ALCOHOL. 



Summarizing briefly the results of preliminary observations it 

 was found that the most satisfactory concentration of i-Amyl 

 alcohol when used with exposures of three to eight minutes, was 

 between 0.7 and 0.9 vol. per cent. Solutions of this strength 

 are sufficiently toxic to prevent many but not all of the eggs 

 thus treated from developing to a larval stage. Solutions weaker 

 than 0.7 vol. per cent, permit practically all eggs to proceed to 



i -AMU. ALCOHOL. 



PLOT OP THE CUHVB OP SUSCEPTIBLE AND BESSHm* PRASTO OF THE 

 MT1STHO SEA-UBCH1H BOC3 WHEtl SUBJECTED TO 0.8 VOL PEH OETfT i-AMYL 

 AHJOWL FOB EfGffr HIHUTB AT SUCESSIVE TEH MMDTB 



the blastula stage with these exposures, with little appreciable 

 difference. At i.o vol. per cent, not more than 20 per cent, of 

 eggs form free-swimming blastulae even when exposed at the 

 period of highest resistance; (e.g., 30 to 40 minutes after fertili- 



