Mr. P. H. Gosse on the Poison-apparatus in the Actiniadae. 311 



excited, whether by direct contact or through the medium of wire, 

 do not at once subside. When the Umbs are withdrawn from the 

 influence of the Actinia in the first experiments, or removed from 

 the wire in the last, strong muscular contractions continue to take 

 place for from three to five minutes. 



All the varieties of Actinia which have hitherto been made the 

 subject of experiment, have given similar evidence of electrical power, 

 but by no means in an equal degree. The large varieties are found, 

 in proportion to their size, much feebler than those of less dimen- 

 sions, and any attempt to succeed in the experiment with the copper 

 wire has failed with them. 



A somewhat similar observation has been made by Dr. John Davy 

 regarding the Torpedo, for he tells us (Philosophical Transactions, 

 1834, p. 548) that he has seen strong vivacious fish which made 

 great muscular exertions in the water, almost or entirely destitute of 

 electrical action. 



It is obvious that in creatures of such moderate dimensions as 

 Actiniae, of so peculiar a form and of such feeble power, much dif- 

 ficulty is to be expected in demonstrating the other experimental 

 effects which animal electricity is capable of producing in common 

 with other electricities, viz. magnetic deflection, — magnetising of 

 needles, — spark, — ^heating power, and chemical action ; and it must 

 be admitted that all experiments hitherto undertaken on this subject 

 have been attended with negative results. I hope, and indeed expect, 

 when further opportunities are afforded of examining these creatures 

 in health and vigour in their native })ools, to obtain more satisfactory 

 results on these points, when I shall look forward to the pleasure of 

 making a further communication on the subject. 



February 4, 1858. — The Lord Wrottesley, President, in the Chair. 



" Researches on the Poison-apparatus in the Actiniadce.** By 

 Philip Henry Gosse, Esq., F.R.S. 



The organs which have been termed " thread-cells," '* thread- 

 capsules," "urticating organs," "lasso-cells," &c., I propose to call 

 cnidce. They are found in various tissues of the body, but are 

 specially localized in two sets of organs, which I call craspeda and 

 acontia. The craspeda are gelatinous cords connected throughout 

 their length with the free edges of the muscular septa. The acontia 

 are somewhat similar cords, but free throughout, except at their 

 base, where they are inserted into the septa. The cord-like appear- 

 ance of these latter organs is, however, illusory, as each is a narrow 

 ribbon with involute margins. Both the craspeda and the acontia 

 are composed of a clear plasma, in which many cnidce are crowded. 



The craspeda appear to be universally possessed by this tribe of 

 animals, but the acontia are Hmited to a few genera, principally 

 Sagartia and Jdatnsia. They are ejected from the body of the 

 animal, and are again withdrawn. 



For the emission of these organs special orifices exist, which I 

 term cinclides. These are minute perforations of the muscular 



