NaturaUH'tstorical Collections. 297 



est trace of any nervous filaments in coonection with the spots. And the author 

 further remarks, that though viewing the phenomenon under circumstances more 

 advantageous than those which occurred to San Giovanni, namely, when sepa- 

 rated from the body of the animal, and under the microscope, with a strong re- 

 flected light passed through the mucous membrane wliile the spots were in action, 

 he could not succeed in discovering any opening in them, even during the great- 

 est dilatations ; indeed, the spots seemed almost as opaque when dilated as when 

 contracted. 



. " That I might ascertain," says Dr. Coldstream, in his unpublished memoir, 

 " whether or not the motions of the spots were now (after apparent death had taken 

 place) carried on by the influence of external agents, independently of any nervous 

 power emanating from the animal itself, I cut, from a part of the mantle where the 

 contractions and dilatations were very strong, a piece of the membrane or layer con- 

 taining the spots, about g-lOths of an inch square; this I separated completely from 

 the animal, and placed it in a watch-glass immersed in sea-water in another vessel. 

 To my astonishment, I saw that the spots in the separated poition continued in 

 as lively motion as when connected with the animal. No change, either in the 

 velocities or extent of their motions, could be perceived. Some spots just on the 

 edges of the separated piece, seemed to have been half cut through by the scissors 

 with which I removed it ; such did not contract ; but all the others in the piece 

 pioved in the very same manner as before. 



" I now removed the watch-glass, containing the separated portion, to the 

 stage of a microscope, and examined the spots with powers of 100 and 150, 

 This, however, gave me no advantage. I saw nothing more than I had previous- 

 ly observed with the naked eye. San Giovanni has compared the appearance of 

 the structure of the spots to that of felt ; but I could not satisfy myself that this 

 was the case in those examined, although I passed through the membrane a very 

 Strong light. I saw that the spots were very thin bodies, attached to the mucous 

 coat of the integument ; that they had no connection with the epidermis ; that, 

 in dilating, their edges passed over, or under each other indiscriminately ; that 

 their edges were extremely sharp and well-delined ; that they never were increas- 

 ed in thickness during dilatation ; and that no vessels carrying coloured fluids 

 entered them. I could not discover, indeed, any thing like either vessels or ner- 

 vous filaments connected with any part of the integument of the animal, and I 

 feel assured, that from the great size of some of the spots which I had under the 

 microscope, I must have seen at least a few vessels carrying dark-coloured fluids 

 entering the mucous coat, had it been from such a source that the increase in size 

 of the spots was derived. 



" The separated piece of the mucous coat, with the palpitating spots, remained 

 Ainder my microscope, exposed to a strong reflected light, for three quarters of an 

 hour, during which time I could perceive no alteration in its appearance, or the 

 strange phenomena it presented. While the motions of the spots were very brisk, 

 I suddenly removed it to a dark place, where it remained fifteen minutes. O^ 

 bringing it again to the light, I found that all motion had ceased ; most of the 

 spots were in a state of contraction ; but, on allowing it to remain for three mi- 

 rtutes exposed to a moderately strong light, the dilatations again commenced, and 

 were carried on unceasingly for a very considerable time. I repeated these experi- 

 ments with other pieces of the spotted membrane, and always with similar re- 

 sults. At the end of nearly two hours from the time when some of them were 

 removed from the animal, the spots were dilating ; but, in the coarse of a few 

 minutes afterwards, motion finally ceased." 



In his second memoir, recently published, (Ann. des Sciences Nat. XVI. 315.), 

 M. San Giovanni shows that every species of cephalopoda, besides its peculiar 

 zoological characters, is distinguishable from all the others, as well by tlie dif- 

 ferent orders of chromophorous globules, as by the difterent intensity of the co- 



