Dr. Cobbold on the Anatomy 0/ Actinia. 121 



XII. — Observations on the Anatomy 0/ Actinia. ByT. Spencer 

 Cobbold, M.D., Vice-President of the Physiological Society, 

 Edinburgh*. 



No apology we trust is needed as inti'oductory to the following 

 remarks, which have for their object the elucidation of a point 

 upon which much discrepancy of opinion exists. It is distinctly 

 stated in the last edition of Dr. Carpenter's valuable work on the 

 Principles of General and Comparative Physiology (p. 271), that 

 " the stomach is closed at the bottom, alike in the solitary and 

 in the compound Helianthoida," and it is further added (p. 272), 

 " the manner in which they (the young) pass from the ovarial 

 chambers into the stomach, is yet an unsolved mystery ;" the 

 accompanying figure from Dr. Sharpey's article " Cilia," in the 

 ' Cyclopgedia of Anat. and Physiol.,' likewise representing that 

 organ as closed infei'iorly. 



Dr. Johnston, in his well-known Treatise on Zoophytes, says 

 (p. 197), " The mouth leads by a very short and wide passage 

 into a large stomach, which is a membranous bag; there is no 

 intestine, nor any other visible exit from the stomach than the 

 mouth ;" and he has also had the politeness to inform me by note, 

 that his private dissections, which were made simply with the view 

 of understanding the descriptions of others, do not permit him 

 to answer the question as to whether there be any aperture of 

 communication between the digestive cavity and that of the 

 body generally. 



In Prof. Rymer Jones's ' Outline of the Animal Kingdom,' 

 the stomach is described (p. 41) as "a simple bag, closed infe- 

 riorly," and in the figure there given it is thus represented. In 

 the article Polypifera (Cyclop. Anat. and Physiol.), also by Prof. 

 Jones, an illustration of Actinia, taken from Quoy and Gaimard 

 (Voyage de I'Uranie), also conveys the same impression. 



Two only of the several authors which we have consulted in 

 reference to this point show the views just alluded to to be 

 incorrect, viz. Professors Owen and Grant; the former states 

 (Lectures on Invertebrate Animals, p. 87), " The impregnated 

 ova (of Actinia) make their way by the small inferior aperture 

 of the stomach into that cavity, and escape by the mouth of 

 the parent." The latter author says, speaking of Lobularia 

 (see his Lectures on Comp. Anat. No. XL., Lancet, 1833-34, 

 vol.ii. p. 645), " The stomach here, as in many allied zoophytes, 

 forms a distinct membranous tube within the body of the po- 

 lypus, and quite open at its posterior extremity, like the stomach 

 of an Actinia, and each polypus has its distinct ovaries at its 



* Verbally introduced to the Society, Dec. 17th, 1852. See reports, 

 wherein other particulars will be mentioned, and which are purposely 

 omitted in the present communication. 



