INVERTEBRATA, CRYPTOGAMIA., MICROSCOPY, ETC. 765 



Regeneration of the Head in Gastropods.* — Tlie first to make 

 experiments on this subject was the eminent Si:)allanzaui ; and he was 

 followed by Pastor Schaffer, of Eegensburg (1768-1770) ; these 

 observations have been greatly neglected, but Professor Martens does 

 well in referring to them in the note in which he deals with the 

 recently published results of Justus Carriere. This naturalist con- 

 firms the observations of his two predecessors ; eyes, tentacles, labial 

 processes may be completely regenerated, but not the pharynx, or the 

 supra-oesophageal ganglion, the destruction or removal of which is 

 always accompanied by the death of the animal. More scientific than 

 his predecessors, M. Carriere was always careful to see that he had 

 really got, in the removed portion, the organ he intended to take away. 

 Moreover, certain conditions are necessary to attain to complete 

 success ; the animals must be in the most satisfactory vital conditions 

 possible, and must have their requirements in the way of air, food, and 

 water carefully attended to ; the experiments generally fail if under- 

 taken at a time when all the energies of tlie animal are directed to 

 the formation of the generative products ; the beginning of summer 

 and the autumn season are the most satisfactory times. As to the 

 species. Helix nemoralis and H. hortensis give the best result ; H. po- 

 matia is more sensitive, and H. arhustorum and H. fruticum are still 

 more so. Aquatic Pulmonata give frequently unsuccessful results, 

 owing to the fact that fungi are very apt to become developed on 

 their wounds. It may be suggested that the antiseptic treatment can 

 be applied to physiological as well as to pathological operations. 



It is interesting to note that the observer has found that in the 

 case of the eyes, at any rate, the process of regeneration is com- 

 parable to that of the first formation of that organ. There is an 

 invagination of tlie epithelium, the formation of a closed vesicle, the 

 primitive cylindrical cells become partly converted into corneal cells, 

 and i^artly into rods and cones. The complete regeneration of the 

 eye takes from fifty to sixty days. 



Activity and Structure of the Muscles of Mollusca Acephala.t — 

 M. Constance has experimented on the scalloj?, on oysters, on Anomia, 

 Pectunculus, Venus, Cardium, Mytilus, by pricking, striking, by induc- 

 tion currents, and by changes of temperature, and finds that of these 

 agents the current of electricity is the most powerful and constant in 

 its action. The muscles consist partly of striated fibres in Pectcn ; in 

 the rest of these Mollusca the striated muscle is replaced by smooth 

 fibre of a special kind ; in the Dimijaria the two kinds may be distinct. 

 Both contraction and extension are voluntary actions, and can bo 

 increased or rendered independent by ammonia vapour, chloroform, 

 &c., which, together with changes of temperature, cause various 

 degrees of paralysis of the- sensitive organs. 



Pedal Glands of the Tellinidse. J — In Tellina (T. haltica) 

 M. Barrois finds a small posterior opening on the foot, leading into 



• ' Niiturforscher,' xiii. (1880) p. 272. 



+ ' Bull. Soc. Acad, do Urcst,' 1879. Sec ' R.v. Sci. Nut.,' ii. (ISSO) p. 117. 



X ' Bull. Sci. Uep. Nord,' iii. (iSSO) p. IKS. 



