62 THURLOW C. NELSON 



either being ignored or else appropriated without giving proper 

 credit. Much of the value of this work of Barrois lies in the 

 thorough critical analysis of all former w^ork which it contains. 

 The historical summary is quite complete to date of publication. 

 Most of his results will be considered in their proper connection 

 on the following pages, but it may be said in passing that the 

 investigations covered an exhaustive study of many forms, deal- 

 ing with the anatomy, histology, chemical composition, and the 

 physiological significance of the style and its attendant structures. 

 The weakness of this contribution to the subject lies in Bar- 

 rois' failure rightly to interpret the facts w^hich were before 

 him. He observed that the style was pushed forward into the 

 stomach, there to be dissolved under the action of the gastric 

 juice. He believed that the resulting viscous mass formed a 

 sort of cement, which surrounding the sand grains and other 

 foreign materials present, encrusted them, and thus prevented 

 injury to the delicate lining of the alimentary canal. The gas- 

 tric shield was believed by him to have a protective function 

 similar to that of the ' Trichter' of insects. 



Pelseneer, in Lankester's Treatise on Zoology ('06) and in 

 his own earlier paper ('91) follows Barrois, and believes that the 

 function of the style is to lubricate the alimentary mass. 

 Schultze ('90) accepts the results of Barrois in their entirety, 

 while Kellogg ('92) disagrees with both Barrois and Pelseneer, 

 since where large amounts of sand are ingested the style could 

 not form a sufficient protective covering. Coupin ('00) thought 

 that the mucus of the style might serve to surround sharp par- 

 ticles and thus protect the epithelium. 



G. A mass of enzyme, or of enzyme and mucus. Anton de Heide 

 (1686), the discover of the style, hazarded the guess that it 

 might be a mass of digestive fluid, but made no attempt to de- 

 termine the fact. Wilson ('77) believed the style to be a mass of 

 oesophageal mucus and gastric juice, but did not demonstrate 

 any action of the style substance on food material. 



The first attempt to determine the presence of enzymes in 

 the style was made by Coupin ('00). He believed that the style 

 was a mass of mucous substance, saturated with digestive fluid, 



