338 RALPH S. LILLIE. 



Deviation in either direction from the physiological norm would 

 presumably impair the power of development. 



GENERAL DISCUSSION. 



I shall now discuss somewhat more fully the general physio- 

 logical significance of the above abnormalities and their rela- 

 tions to analogous conditions elsewhere. The above condition, 

 described in general terms, is essentially one of lowered suscep- 

 tibility to agencies which ordinarily call forth a definite re- 

 sponse. Similar conditions exist in other cells and tissues. 

 There are also cases w r here a tissue is normally irresponsive to 

 certain agencies or conditions, to which however it may be 

 rendered responsive by certain forms of artificial treatment. 1 

 It seems probable that in all of these cases the condition of the 

 plasma membrane is the essential factor which determines 

 whether the cell or tissue responds to the agency in question or 

 not. This structure, as the most external layer of the cell, 

 is the part most accessible to artificial modification; and if its 

 condition of permeability and electrical polarization plays the 

 controlling role in cell-processes which modern investigation 

 tends more and more to indicate, knowledge of the means by 

 which its properties may be altered at will becomes a matter 

 of the highest importance for both the theoretical and the prac- 

 tical aspects of biology. 



The abnormalities under consideration appear typically 

 in the eggs of Asterias forbesii toward the close of the breeding 

 season. Eggs are abundant at Woods Hole in early June. 2 

 During the greater part of this month they exhibit as a rule 

 a normal response to fertilization; and if left unfertilized in 

 sea-water at 20 they undergo the above described coagulativc 



1 Instances of this are seen in various phenomena of sensitization. A good in- 

 stance is the hypersensitiveness to contact induced in frog's skeletal muscle by 

 isotonic solutions of sodium citrate, tartrate, sulphate, and certain other salts. 

 Cf. J. Loeb, American Journal of Physiology, 1901, Vol. 5, p. 362. 



2 In former years a considerable proportion of starfish collected in August and 

 September have yielded numerous normal eggs. Probably these starfish \vi-re of a 

 different species from the above presumably A. rnl^nris. During the last few 

 years this form seems to have become rare in the neighborhood of Woods Hole, 

 and eggs have been difficult to obtain later than June. Two species of Astri-ia*, 

 forbesii and vulgaris, are recognized as occurring in thi- region; cf. II. L. (.'lurk, 

 Bulletin of the U. S. Fish Commission, 1902, p. 552. 



