464 ALVALYN E. WOODWARD 



agglutinated by the egg secretion of the same species, while 

 sperm of S. franciscanus are agglutinated not only by secretion 

 from eggs of the same species, but also by that of S. purpuratus. 



Miss Margaret V. Cobb (unpublished) discovered that the 

 eggs and egg-water of Cumingia produce positive chemotactic 

 response on the part of the sperm. 



These results are summarized in table 1 and warrant the 

 assertion that the eggs of at least four phyla of marine animals 

 secrete into the sea-water substances significant either in their 

 effects on sp^rm or in fertilization. 



B. Concerning the secretions of Asterias and Arhacia in particular 



While these facts indicate that the egg secretion may play 

 an important role in fertilization, they do not make clear either 

 the nature of the secretion itself or the manner in which it oper- 

 ates. It may be one homogeneous substance or a mixture of 

 two or more specific substances. 



Conceivably, there are three ways in which the problem can 

 be attacked: 1) by physiological analysis of the secretion; 2) 

 by general chemical analysis; 3) by the removal of specific ele- 

 ments from the secretion and the further analysis of their indi- 

 vidual properties. 



1. Physiological analysis, a. The secretion is necessary for fer- 

 tilization in some species. As stated above, Lillie gave the name 

 ' f ertilizin' to the egg secretion because he considered its presence 

 absolutely necessary for the fertilization of Arbacia eggs. Just 

 found it equally indispensable for the fertilization of Nereis 

 and Platynereis. 



Loeb ('15) criticised their conclusion on the ground that the 

 washed eggs had stood so long after shedding that they were 

 dead, but the following experiment disposes of this objection. 

 The eggs from ripe starfish were divided into two lots. One lot, 

 A, was put into a finger-bowl of sea-water as control. The rest 

 were placed into a large glass tube, closed at the bottom with 

 chamois skin. The upper end was similarly closed except for 

 an opening into which fitted closely a smaller tube through which 



