SENSORY EPITHELIUM OF MICROSTOMA CAUDATUM. 



December 2, 1911. A specimen that had been kept in the 

 laboratory twenty hours after entering the drop of fresh water 

 did not leave it although it came in contact with the margin of 

 the salt solution six times (text-figure 7-6). 



January 13, 1912. A specimen that had been kept in the 

 laboratory twenty-four hours after entering the drop of fresh 

 water did not leave it although it came in contact with the salt 

 solution six times (text-figure 7-^). 



None of these specimens after entering the fresh water left it. 



Group 2-a (specimens placed in fresh water and allowed to 

 encounter a drop of .05 per cent, salt solution). 



November 22, 1911. A specimen that had been kept in the 

 laboratory five days passed five times from the fresh water into 

 the salt solution and did not show any reaction to the latter at all 

 (text-figure 8-a). 



November 20, 1911. A specimen that had been kept in the 

 laboratory six days passed from the fresh water into the salt 

 solution three times and did not show any reaction to the latter 

 (text-figure 8-b). 



FIG. 8. Diagrams indicating the paths of specimens when placed in fresh water 

 and encountering a drop of .05 per cent, salt solution. The dotted line indicates 

 the contour of the drop of .05 per cent, salt solution surrounded by fresh water. 



December 2, 1911. A specimen that had been kept in the 

 laboratory three days passed from the fresh water into the salt 

 solution three times and did not show any reaction to the latter 

 (text-figure 8-c). 



These specimens show a marked difference in their conduct as 



