146 SEA-SIDE STUDIES, 



capsules, filiferous capsules, or urticating cells (Plate III. 

 fig. 5), are organs of urtication, or stinging. The uncritical 

 laxity with which this hypothesis has been accepted may 

 point a lesson. I do not allude to the acceptance of the 

 a^t that certain capsules containing threads are found in 

 Polypes ; but to the acceptance of the alleged purpose, or 

 function, of these capsules. The things are there, sure 

 enough ; but whether they serve the urticating purpose, is 

 another matter. Ever since they were first described by 

 Wagner * Erdl,f Quatrefages, and Siebold,+ they have passed 

 without challenge. They have been detected in the whole 

 group of Polypes, in Jelly-fishes, in the papillse of Eolids, 

 and, according to Van der Hoeven, in Planarioe ; yet, as far 

 as my reading extends, not one single experiment has been 

 made to prove the function so unanimously admitted, not a 

 single test has been applied to strengthen or controvert what 

 was, indeed, very plausible, but only plausible, not proven. 

 Accordingly, no sooner did I submit the question to that 

 rigorous verification which Science imperiously requires, than 

 it became clear to me that my illustrious predecessors — 

 Wagner, Erdl, Siebold, Quatrefages, Ehrenberg, Agassiz, 

 and Owen — men whom the most presumptuous would be 

 slow to contradict, had admitted the point without proof, 

 because it wore so plausible an air. Let me hope the reader 

 will accuse me of no immodesty in thus controverting men 

 so eminent ; he will see that whereas they have only hypo- 



• WiEGMANN's ArcMv., 1835, ii. p. 215. 



t Mueller's Archlv.,\M\, p. 423. 



X Comp. Anat., i. p. 39 (English Trans.) 



