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J. M. D. OLMSTED 



regularly at the end of 7 hours, though much more feebly than 

 when first dissected out (table 1). 



. TABLE 1 

 Synaptula intestine in sea-water at 27° C. 



a. Effect of change of temperature on intestinal pulsation. The 

 effect of change of temperature on living material has shown 

 than van't Hoff's, or the R. G. T., rule holds good in the organic 

 as in the inorganic world (Putter, '14). The intestine of Synap- 

 tula is no exception. The curves in figures 1 and 2, which show 

 the effect of change of temperature on the rate of pulsation, are 

 typical. Qio is found to have the following values: 



16°-21° =3.24 

 21°-26° = 2.56 

 26°-36° =1.4 



These values for Q 10 are of the order of magnitude of those for 

 chemical processes, as Crozier ('16 a) found for the rhythmic pul- 

 sation of the cloaca of certain holothurians. This series also 

 shows the phenomenon to which Snyder ('11) has called atten- 

 tion, viz., Qio is greater for lower than for higher temperatures. 



b. Effect of chemicals on intestinal pulsation. The effect of 

 chemical agents on rhythmic pulsation has been the subject of 

 considerable investigation (see Crozier, '16 a, for literature). 

 The following experiments on the intestine of Synaptula give 

 results which are similar to those obtained by Crozier for 

 Holothuria. 



The average time for ten beats in artificial sea-water (Mayer, 

 '11, '14), i.e., |M (100 NaCl + 7.8 MgCl 2 + 3.8 MgS0 4 + 

 2.2 KC1 + 2.5 CaCl 2 ) at 27°C. was 29 seconds. This is prac- 



