BY F. ROLAND HAYES, B. SC. 167 



V. The Effect Continued of Immersion on Negative 



Geotropism 



For the experiments on immersion some 2000 adult speci- 

 mens of L. littorea were collected at low tide level and placed 

 in quart jars, 75 individuals to each jar, and there was added 

 a supply of the fronds of Fucus with fruiting buds attached 

 sufficient to serve as food for a long time. 



The mouths of the jars were covered with carefully para- 

 ffined copper wire gauze. The jars were then suspended from 

 the breakwater at the Biological Station, thus undergoing total 

 immersion. No jar was closer than one meter from the surface 

 and from this depth they ranged to three metres. It was not 

 thought that light could have been a factor in any results. 



Controls were used as follows, there being two jars of each 

 control type: 



(I) 10 animals per quart jar; no Fucus. 



(II) 10 animals per quart jar; full supply of Fucus for 

 75 animals. 



(III) 75 animals per quart jar; no Fucus. 



The controls proved effective; no animals died in any 

 control jar nor did any die in any experimental jar. 



A geotropism experiment was conducted on a group of the 

 animals periodically, in an attempt to find a variation due to 

 the physiological change of the periwinkles resulting from their 

 continued immersion. 



Owing to storms which carried away a number of jars and 

 made it necessary to replace several, the experimental results 

 do not form as perfectly graded a series as might have been de- 

 sired. Several long gaps toward the latter part indicate a time 

 when it was impossible to obtain experimental data owing to 

 the factor mentioned. 



Table 5 records the responses showing in this series of tests 

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