480 



possible, is to be laid on a plate of clean glass ; a silk thread is tied 

 round the base of one of the tentacles of an Anthea, and the tentacle 

 snipped off. The mere tentacle separated from the animal to which 

 it belonged is drawn gently across the nerve, or laid upon it, at the 

 upper part: immediately muscular contractions follow in the leg. 

 These contractions cease at once if the portion of the nerve touched 

 by the tentacle be cut off. There can, it seems, no longer be any 

 doubt that the muscular contractions are excited, not by elec- 

 tricity, but by irritant action of the urticating organs of the Anthea, 

 which being more powerful in this respect than other Anemones, 

 has been chosen for experiment, although other varieties give similar 

 results. 



I now see I was in error in supposing that the effect produced on 

 the frog's limb by the Actiniae could be transmitted along a wire. 

 I presume that in preparing the experiment alluded to, which I 

 performed in the open air, at the sea-side, some of the irritant 

 materials of the Anemones, which I had possibly handled, had 

 been brought by my fingers in contact with the nerves, and I was 

 thus deceived. 



I am very happy, however, that I am myself the first to perceive 



and correct this error. 



I remain, &c., 



ROBERT M'DONNELL. 

 W. Bowman, Esq., F.R.S., $c. fyc. 



III. " On the Digestive and Nervous Systems of Coccus hespe- 

 ridum." By JOHN LUBBOCK, Esq., F.R.S., F.L.S., F.G.S. 

 Received Oct. 4, 1858. 



In the early part of last spring I began to investigate the anatomy 

 of this interesting little insect, with the intention of studying only 

 the organs connected with the development of the ova and pseudova. 

 It soon, however, became evident that the structure of the intestinal 

 canal, on the one hand, had been entirely misunderstood by those 

 who had previously examined it ; and on the other, that the nervous 

 system, far from being similar in all specimens, varied in the most 

 extraordinary manner. It is therefore proposed in the present com- 

 munication to give a very brief description of the digestive organs 

 and of the nervous system. 



