90 THURLOW C. NELSON 



In color the crystalline style varies from a clear, transparent 

 structure, like a glass rod, to a deep brown, opaque rod, the 

 color of chocolate. Aside from the presence of an inner core of 

 food material, which may give more or less color to the styles 

 of all species not having a separate caecum, the cortical layers of 

 hyaline matter themselves may contain a diffuse yellow sub- 

 stance. In Anodonta and the adult Ostrea I have invariably 

 found some trace of this color present, even in the clearest 

 styles. In Lampsilis, Modiolus, Martesia, and the very young 

 oyster, the cortical layers are usually as clear as crystal. 



The composition of the style 



Investigation of the composition of the style by the earlier 

 workers— von Poh (1791), Hazay ('81), and Haseloff ('88)— re- 

 vealed the following facts: gelatinous in consistency, the style 

 dissolves readily in water, more rapidly in salt solution. It 

 is coagulated by boiling water, alcohol, and other protein pre- 

 cipitants. It gives the delicate KCN reaction for albumen, 

 and a violet color with the biuret test. 



The most extensive investigation of the structure and chem- 

 cal composition of the crystalline style which has yet appeared 

 is found in the work of Barrois ('89). A chemical analysis of 

 the style by Lambling is included in this paper. The conclu- 

 sions of Barrois are based not only upon many different forms, 

 but what is of equal importance, upon a large number of indi- 

 viduals of each species. In following the color variations of the 

 style this investigator opened over 6,000 individuals of Car- 

 dium alone. Since this work has been given but scant atten- 

 tion by most subsequent writers, the results are given below in 

 some detail. 



The style was found to vary in size with the individual and 

 with the relative proportions of the sac or caecum containing it. 

 The longest style described by Barrois was 7 to 8 cm. in Ano- 

 donta anatina. As found in the marine species the style was 

 usualy of a pale yellow color, while in the Unionidae it was 

 transparent and colorless. Great variation was found in the 



