588 JACQUES LOEB 



Amount of NH^OH used: 



0.05 cc. -^ NH4OH Two larvae found. Practically all the eggs unaltered 



and normal. No membranes 

 0.10 cc. -f^ NH4OH Very few larvae. About half of the eggs unaltered, 



the rest cytolyzed 

 0.20 cc. T^ NH4OH Few larvae. Practically all the eggs cytolyzed 

 0.40 cc. -To NH4OH A large number of larvae, part of which rise to the 



surface 

 0.80 cc. To NH4OH Very few larvae; the rest of the eggs practically all 

 cytolyzed 



These results are easily intelligible in the light of the pre- 

 viously described experiments. The addition of 0.05 cc. -^ 

 NH4OH to 50 cc. m/2 (NaCl + KCl + CaCla) does not affect 

 the eggs in forty minutes, nor does an exposure to the hyper- 

 tonic solution for fifteen minutes. Practically all of the eggs, 

 therefore, remain normal. 0.10 cc. ^ NH4OH is able to affect 

 a number of eggs -in forty minutes, but the exposure of fifteen 

 minutes in the hypertonic solution is too short (see previoils 

 paragraph.) Therefore, the affected eggs perish. They might 

 have developed had they been exposed a little longer to the 

 hypertonic solution. 0.04 cc. t^ NH4OH is- satisfactory for an 

 exposure of forty minutes to the alkaline solution and of 

 fifteen minutes to the hypertonic treatment. This series, there- 

 fore, yields a good crop of larvae, although it is not the opti- 

 mum. 0.8 cc. T^ NH4OH is too high a concentration, for it 

 injures the eggs and only a few survive. 



9. The individual variation of the eggs 



All of these as well as our previous experiments bring out 

 the fact that the individual eggs vary a little in their reaction 

 to the same solution. We are inclined to ascribe this result 

 chiefly to a difference in the permeability of the individual eggs 

 for bases, since it is not to be expected that the surface films 

 of the individual eggs are exactly alike. Another source of 

 variation seems to lie in the unequal distribution of the eggs 

 in the solution, or at the bottom of the dish, whereby the chances 

 for the equal diffusion of alkali or oxygen into the egg are di- 

 minished. 



