Martin, A Note on the Occurrene of Nematocysts and Similar Structures etc. )>7J 



to so arrange the Nematocyst under the skin that it points in the 

 right direction, 



(2) or the explanation may be a simple mechanical one, viz., 

 that the structure and the shape of a hydroid Nematocyst will 

 always set it a certain angle under certain conditions of pressure, 

 and that the resultant of these forces leads to the Nematocyst 

 under the skin always pointing in the right direction. One cannot 

 help feeling however that this problem of the arrangement of 

 Nematocysts is one which should appeal to physiologists. 



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18* 



