156 L. V. HEILBRUNN. 



hypertonic sea- water" is used to designate 50 parts (by volume) 

 of sea-water plus 8 parts of 2.5 N NaCl. 



August 21. Two small stender dishes, A and B, were used. 

 A contained 29 c.c. of NaCl hypertonic sea-water made up on 

 August 1 8, B contained 29 c.c. of NaCl hypertonic sea-water 

 freshly prepared. At 10:04 A.M., 5 drops of egg suspension 

 were added to A, and a similar amount to B. 



The following measurements of egg diameters were made at 

 the times indicated. In making these measurements a Spencer 

 movable scale micrometer was used. It was not found possible 

 to obtain any very great accuracy in the use of this instrument. 

 If the eggs are not subjected to pressure of the coverslip, they 

 tend to move their position slightly. After various attempts 

 I reached the conclusion that the use of the movable scale was 

 inadvisable, especially as the usual difficulties of focusing made 

 very accurate measurements out of the question. Accordingly 

 the measurements were made with the scale stationary. No 

 great claim for accuracy is therefore made, but the error is not 

 over one micron. Fortunately the difference between the 

 diameters of the two sets of eggs is markedly greater than the 

 experimental error of the method. The measurements were 

 made at a magnification of about 650 diameters. 



DIAMETERS OF EGGS IN A. 



70 /j. 70.5 M at 10.25 A.M. 



69 71 at 10.28 A.M. 



69 70 at 10.29 A.M. 



67.5 69 at 10.30 A.M. 



69 69 at 10.51 A.M. 



68 71 at 10.53 A.M. 



68 71 at 10.55 A.M. 



69 69 at 10.57 A.M. 

 68 69 at 10.58 A.M. 



Average 69.2^. 



DIAMETERS OF EGGS IN B. 



66 fj. 66 M at 10.32 A.M. 



67 68 at about 10.35 A.M. 

 66 67 at about 10.35 A.M. 

 66 66 at about 10.35 A.M. 

 66 66 at ii. 15 A.M. 



70 70.5 at 11.17 A.M. 



