Surface Layer in the Living Egg Cell. 41 



point is found at which the loop just disappears from view. The 

 distance of the loop below the meniscus is then measured with a 

 centimeter scale laid along the tube, giving the first reading. 

 A second reading is obtained after the addition of a measured 

 amount of the diluent, and the data required for substitution in 

 the equation for the corrected reading is at hand. The readings 

 and calculations require but two or three minutes. In the zone 

 of most accurate measurement, with suspensions of such opacity 

 that the loop disappears between 1 and 4 cm. below the surface, 

 repeated readings may be made with a variation of about one milli- 

 meter, an error of less than 10 per cent. The wire loop, which 

 alone comes in contact with the bacteria, may be flamed after 

 each determination, thus reducing the danger of contamination to 

 a minimum. 



A more complete explanation of the method, with a description 

 of the more convenient and accurate instrument shown at the 

 meeting will appear in a forthcoming number of the Journal of 

 Experimental Medicine. 



23 (1483) 



Some studies on the surface layer in the living egg cell. 

 By Robert Chambers. 



[From Cornell University Medical College.] 



The results recorded here were obtained through the use of 

 Barber's mechanical pipette holder somewhat modified for micro- 

 dissection purposes. 



The cells experimented upon were the egg cells of the starfish 

 and of the sea urchin. The eggs, which are somewhat over 1/10 

 of a millimeter in diameter, were placed in a drop of sea water 

 hanging from the roof of a moist chamber. The microscopically 

 fine tips of the glass dissecting needles projected into the moist 

 chamber and up into the hanging drop. By manipulation of the 

 screws of the mechanical pipette holder the cells in the hanging 

 drop could be dissected with considerable accuracy and an esti- 

 mate ascertained of their physical consistency. Detailed accounts 



