author's abstractt of this paper issued 

 by the bibliographic service, april 20 



ON THE ORIGIN, NATURE, AND FUNCTION OF THE 

 CRYSTALLINE STYLE OF LAMELLIBRANCHSi 



THURLOW C. NELSON 



From the Zoological Laboratory oj the University of Wisconsin 



SEVENTEEN FIGURES 



CONTENTS 



1 . Introduction ; 53 



The crystalline style • 54 



Historical 57 



Materials and methods 63 



2. Origin 65 



Gross structure of the style-bearing organs 65 



The gastric shield 71 . 



Nervous and vascular connections 73 



Histology of the style sac 74 



The ciliary mechanism 76 



The secretion and formation of the style 80 



Embryology of the style-bearing organs 87 



3. Nature 89 



Description of the style 89 



Composition of the style 90 



Nature of the gastric shield 96 



The Spirochaetes of the crystalline style 97 



4. Function 98 



5. Summary and conclusions 107 



Bibliography 108 



1. INTRODUCTION 



''What has not been written concerning the crystalline style, 

 and in how many ways has not the mind of man sought to under- 

 stand its true meaning, and to get to the bottom of its nature I"^ 



With these words a recent investigator (Matthias, '14) sums 

 up well the history of the crystalline style of the lamellibranchs. 

 Few molluscan structures have excited more interest among 



1 Submitted as thesis for the degree of Doctor of Philosophy, June, 1917. 



2 Translation is mine. 



53 



