CRYSTALLINE STYLE OF LAMELLIBRANCHS 97 



small amount of digestive juice, it slowly softens and, after sev- 

 eral days to a week, disintegrates. It is therefore, a structure, 

 which, unlike the style, is not renewed at the commencement of 

 feeding activity. 



The Spirochaetes of the crystalline style 



As is well known, the crystalline style in many species of 

 lamellibranchs harbors a large spirochaete, which has been put 

 by Gross ('10) in a separate group, the Cristispira. My own 

 observations have been on Cristispira balbiani Certes, from the 

 oyster, and C. anodontae Keysselitz, from Anodonta grandis, one 

 of the largest spirochaetes known. Why they occur in the style 

 and whether or not they are harmful to' the host are questions 

 which cannot be considered in th£ present work. These organ- 

 isms are mentioned here only because they throw some additional 

 light on the consistency of the style substance. 



Examination of a fresh style of Ostrea or of Anodonta shows 

 the spirochaetes in great numbers, moving back and forth with 

 their characteristic corkscrew motion. The majority of these 

 Protozoa occur at or near the surface of the style, but apparently 

 they have no difficulty in passing inward to the core and back 

 again through the substance of the cortical layers. Fixed sec- 

 tions show them in all parts from the core outward 



In Anodonta, at least, these organisms are usually found in 

 the greatest numbers in the bubbly mucous in the end diverti- 

 culum of the style sac, becoming much fewer toward the stomach. 

 It is probable that their presence near the anterioj end of the 

 style and in the stomach is due to the continual forward move- 

 ment of the former, and not to choice on the part of the spiro- 

 chaetes. 



A striking peculiarity in their distribution lies in the fact 

 that the styles of some species appear to be wholly free from 

 them. Such is the case in the styles of Lampsilis luteolus and 

 L. anodontoides that I have examined, though in one instance 

 twelve spirochaetes were discovered in a style of L. anodontoides. 



JOURNAL OF MORPHOLOGY, VOL. 31, NO. 1 



