IMMUNITY AND SUSCEPTIBILITY OF SEA-URCHIN EGGS. 22/ 



But furthermore, whatever the morphological elements may be, 

 it must also be admitted that in the processes leading up to and 

 culminating in cleavage, we are dealing with chemical and elec- 

 trolytic and consequently also with osmotic phenomena, coex- 

 isting with those of surface tension. That these first two which 

 condition the other two are, however, not uniform, but, rather, 

 are varying, /. c., rhythmical, during that period must be ad- 

 mitted to explain the observed rhythm in morphological changes. 

 The experiments herein described serve the purpose then of 

 testing the above-mentioned hypothesis of the existence of a 

 liquefaction during the event of cleavage, and of a rhythm of in- 

 creasing immunity up to and of marked susceptibility during that 

 time. To this end use was made of ethyl ether, HC1, KC1, 

 NaCl and sodium citrate solutions. 



THEORIES OF THE NATURE OF THEIR ACTION. 



From the position that has been taken in this and a previous 

 paper that, inasmuch as in protoplasm we are dealing with col- 

 loidal (probably also electrolytic) particles in solution, we there- 

 fore in segmentation necessarily have to do ultimately with the 

 relations of two kinds of energy, osmotic and surface, and that 

 the cleavage process itself depends upon the existence of an un- 

 compensated potential difference between these, from this it fol- 

 lows that this potential difference might be caused in eitlier of two 

 ways, viz., at the same time that either one is kept constant, by 

 changing the other, /. c., either increasing the osmotic or decreas- 

 ing the tension factor, the former being identical with the energy 

 of the particles in solution, the latter with that of the solvent. 

 The theories also which we find advanced in order to explain the 

 nature of stimulation seems to us to be in complete agreement 

 with this view. For example, we find the statement that " stimu- 

 lation consists in the precipitation, /. c., gelation, of colloidal 

 particles and is due in the case of positively charged particles to 

 the negative ions, i. c., to the charge; 1 the inhibition of this 

 stimulation, /. c., what in some cases is termed poisoning, to the 

 positive ions"; for negative particles the converse would hold 



1 Mathews, A. P., "The Nature of Nerve Stimulation, etc.," Science, March 28, 

 1902. * 



