98 THURLOW C. NELSON 



Also, I have never found any spirochaetes in the styles of 

 Modiolus, though oysters attached to them are heavily infected. 

 Finally, the spirochaetes, unlike most protozoans, are able to 

 resist the action of the digestive ferments of the alimentary 

 canal, and are apparently unacted on by the juices in the stomach. 



4. FUNCTION 



The conclusions of former investigators regarding the function 

 of the crystalline style have been considered in the historical 

 summary (p. 57). The inadmissibility of most of these must be 

 evident at once, and they will be dismissed without further com- 

 ment. A critical examination of the others is reserved until 

 after the presentation of my own conclusions and the evidence 

 upon which they are based. 



Realizing that the misconceptions of many former workers 

 have been due largely to abnormal and unfavorable conditions 

 surrounding the mollusc under observation, my own endeavors 

 have been to study the style in its physiological relationships 

 while the animal was still in or near its natural environment. 



In this I have been greatly aided by the opportunity afforded 

 by the floating laboratory for oyster research of the New Jersey 

 Agricultural Experiment Station. As this laboratory is stationed 

 over the natural beds of the oyster, with clams and mussels 

 within a few feet, it was possible to remove a bivalve from its 

 natural environment and within two or three minutes to have it 

 opened and under observation in the laboratory. Too much 

 emphasis cannot be laid on the necessity for study of this nature 

 in determining the physiological significance of the style. 



The first investigations covered a determination of the factors 

 in the normal environment which bring about the secretion or 

 dissolution ■ of the style. 



The ribbed mussel, Modiolus, occurs most commonly in 

 bunches along the banks of tidal creeks and estuaries. Natural 

 oysters also may be attached to these clusters. From their po- 

 sition on the bank, the molluscs are necessarily exposed from 

 three, to as much as six or eight hours between successive high 

 tides, during which time, of course, no feeding takes place. 



