THE EFFECTS OF HYPERTONIC SOLUTIONS. 
447 
The Effects of Hypertonic Solutions upon the 
Fertilised Eggs of Echinus (E. esculentus 
and E. acutus). 
By 
.1. Gray, B.A. 
Scholai’ of King's College, Cambridge. 
(From the Laboratory of the Marine Biological Association, Plymouth.) 
With Plates 24 to 27 and 4 Text-figs. 
PAGE 
I. Introduction ..... 447 
II. Methods ...... 449 
III. Descriptive ..... 450 
IV. Summary of Experimental AYork . . . 466 
Comparison of Results with those of other Investi- 
gators ...... 466 
VI. Hybridisation and Pathology . . . 469 
VII. Theoretical ..... 471 
VIII. Bibliography ..... 475 
IX. Explanation of Plates .... 477 
Jn the ‘ Proceedings of the Cambridge Philosophical 
Society,’ vol. xvi, part v, 1911, a preliminary account was 
given of the cytology of the eggs from which the various 
hybrids obtained from the three species of Echinus — E. 
esculentus, E. acutus, and E. miliaris, have been 
reared by Shearer, De Morgan and Fuchs (15). 
It was shown that whereas the first segmentation division 
of an egg of E . esculentus fertilised by the sperm of E. 
acut us was quite normal, that of the reverse cross showed 
certain abnormalities. 
