FERTILIZATION-REACTION IN ECHINARACHNIUS PARMA. 28l 



yond the optimum for membrane lifting, and which show thick 

 jelly-like cortices without the wide perivitelline space so character- 

 istic of both inseminated and butyric acid activated eggs, are still 

 capable of fertilizaton although their development subsequent to 

 insemination is abnormal. This response to insemination of these 

 three classes of butyric treated eggs activated, exposed but not 

 activated, and over-exposed constitutes a criterion in the analysis 

 of activation as striking as the visible structural changes in the cor- 

 tex of inseminated eggs which are the criterion of normal sperm 

 activation. It seemed, with the aid of this criterion, desirable to 

 attempt a further analysis of the activation process -in Echinarach- 

 nius, and to this end the writer has made observations, herewith 

 reported, on the duration of the fertilization capacity of butyric 

 acid treated eggs. At the same time it was possible to study the 

 rate of cytolysis of butyric acid treated eggs in sea-water as com- 

 pared with normal eggs in sea-water. The results of these two 

 lines of observations on butyric acid treated eggs give a possible 

 explanation of the nature of butyric acid activation in Echina- 

 rachnius which involves the whole theory of activation. Follow- 

 ing, therefore, the presentation of the observations on cytolysis 

 (Part II.) and those on the duration of fertilization capacity 

 (Part III.) is a general discussion of these results and their 

 bearing on the theory of activation (Part IV.). 



II. OBSERVATIONS ON THE CYTOLYSIS OF BUTYRIC ACID 



TREATED EGGS. 



Now, it is a well-known fact that marine ova normally shed in 

 sea-water when physiologically " ripe " for fertilization in sea- 

 water cytolyze at a rate which varies with different species. Cyto- 

 lysis of the uninseminated egg in normal sea-water is a natural 

 phenomenon. Thus, according to Goldfarb: 



" The consummation of the various deteriorating changes in 

 ageing eggs is cytolysis and death. 



" Cytolysis of sea-urchin eggs under the influence of various 

 experimental conditions, such as saponin, salycyl, aldehydes, 

 propyl alcohol, distilled water, etc., have been carefully described 

 by Loeb. Loeb speaks of two methods of cytolysis, which he 

 calls ' white ' and ' black.' 



