The Energy of Segmentation 305 



with this mode of determination, ff and U^-U^ will not have 

 been kept apart; accordingly it is quite possible that during the 

 event of cleavage heat is absorbed from the environment, that the 

 internal energy will have increased by a certain amount. How- 

 ever, to determine the exact value of such an increase would seem 

 to be impossible. Yet experiment makes clear that there is a 

 change in pressure. To what is this due .^ Equation [8] shows 

 that in general such a change must be due to the fractional change 

 in some other intensity; for, with U^- 11^=0, and W = pv, by 

 substitution in [8] we get 



T pdv dp dl 



pv = I ^jy- or ^L- = 

 ^ dl pi 



That this change should be the result of a change in tempera- 

 ture is impossible if the view is correct that this last intensity is 

 constant; yet correlative change there must be, and the evidence 

 is that this is in the chemical conditions, 



RECORD OF EXPERIMENTS 



The following is an epitomized record of the experiments per- 

 formed,^'' showing what solution-concentrations were sufficient to 

 inhibit the earher cleavages; the results will be found to show a 

 fairly close agreement. The figures given here are simply those 

 of the concentration, obtained in each case by starting with a cer- 

 tain number of cc. of a § m. sugar solution in sea-water for each 

 lot of eggs transferred, and then diluting this amount with a cer- 

 tain measured amount of sea-water, plus the i^ cc. of sea-water 

 necessary for transferring the fertilized eggs. The pressures thus 

 obtained are here not reduced to atmospheres; that is done only 

 for the typical experiment in which the computation is carried out 

 completely. In all of these the eggs in the control segmented very 

 uniformly and well. 



Experiment I, July 15: First segmentation stopped in sol. 

 ID cc. sugar sol. plus 11 cc. sea-water plus i^ cc. s. w.,^^ and in 



'"The experimentation was done in the Marine Biological Laboratory at Woods Hole, in the summer 

 of 1905. 



"s. w., sea-water. 



