VI PREFACE 



of the fertilization membrane, it having been forgotten or ignored 

 that these were first described some forty years ago. (2) References 

 to brief and scrappy papers which have not been followed up. 

 Some exceptions to this rule will be found in chapter 7, Metabolic 

 and Other Changes at Fertilization. (3) References to papers which 

 I do not think good. Where work has been, or might be, wrongly 

 accepted as true, I have drawn attention to the errors in it. But, in 

 general, such papers have not been mentioned. 



Every writer of a book on fertilization must be uncomfortably 

 aware of his sins of omission and commission, so great is the 

 labour imposed by the literature on the subject. The author is no 

 exception and proffers his apologies. 



Index of Plants and Animals. There are three columns in this 

 index. The first gives the name of the organism, some of the 

 familiar synonyms and the English or American names, when 

 known. The second column states the order and class to which 

 the animal or plant belongs. When I was a child, my father 

 expected my sisters and myself to know the Latin names of 

 the plants, bees and butterflies which we had to collect. It 

 was inevitable therefore that an Index of Plants and Animals 

 should figure in this book. But there was a more cogent 

 reason. Reference will be found in several places to the specificity 

 of fertilization, to the alleged specificity of the polysaccharides 

 in egg jelly, and to interspecific, intergeneric and interphyletic 

 cross-fertilization. We cannot think clearly about such subjects, 

 nor describe and compare experiments relating to them, unless 

 we are reasonably sure of the identity of the organisms concerned. 

 Reference to the Echinoid synonyms shows that this is not always 

 easy. A diverting example of the confusion which springs from 

 careless nomenclature is to be found in a paper by Mitchison & 

 Swann (19546), which is discussed, for other reasons, in chapter 

 8. These authors measured the elastic modulus of the cortex of the 

 unfertilized egg of the sea-urchin Arhacia lixula (Linn.). With the 

 aid of their own and E. N. Harvey's measurements (193 1), they 

 calculated the tension at the surface of the unfertilized egg of an 

 'American species of Arhacia' (p. 469), which they refer to as 

 Arbacia pustidosa. Arbacia lixula (Linn.) and Arbacia pushilosa 

 (Leskc) arc synonyms for the same sea-urchin, although Harvey 

 actually used the eggs of Arbacia punctulata (Lamarck) in the 

 experiments in question. 



