MARTINI, ON SENSE-NERVES IN APHLSIA. 123 



repeated, conducted in a similar manner, and without any 

 change in the manipulation, and with a portion of the same 

 quicksilver, but which has been previously heated, not a 

 single living organism will be produced. 



On the Anatomical Constitution of the Nerves of Sense 

 in the Genus Aplysia. By M. Martini. 



(' Comptes reudus,' Oct. 22, 1860, p. 635.) 



It is well known that the integuments, tentacles, and 

 mouth of these Gasteropoda are extremely sensitive to the 

 least mechanical stimulation. I have also noticed the effects 

 of a weak galvanic current applied to the organs of sense ; the 

 excitation of two closely approximated points, beyond the 

 oesophageal ring, induces the contraction of nearly the entire 

 muscular layer of the integument and foot. This fact. shoAvs 

 that not only the ganglia of the oesophageal ring, but the 

 other ganglia also are capable of reflecting centripetal into 

 centrifugal actions, and of becoming the central pole of a 

 nervous circulation, as has been proved by ]M. Flourens from 

 physiological proofs, and by JNI. Jacubowitsch from anatomi- 

 cal facts. 



Moreover, the nerves of the organs of sense, that is to say, 

 in Aplysia, the nerves of the integument, of the tentacles, and 

 of the mouth are furnished v/itli numerous ganglionic enlarge- 

 ments. In the cutaneous nerves these are found at almost 

 every point of the ramifications and anastomoses, and in the 

 nerves of the tentacles also in the course of the branches and 

 of the extreme filaments. 



Tlie ganglionic enlargements are of considerable size, 

 relatively to the branches of the nerve. They are of a yellow 

 colour, and composed of ganglionic cells, Avhich are, for the 

 most part, unipolar. 



It should be remarked, that in the nerves of the tentacles 

 ganglionic cells are always present, even in nervous filaments 

 in the centre of the fibres ; and that the terminal nervous 

 plexus is formed chiefly of multipolar cells. Lastly, the gan- 

 glionic structure extends to the primitive fibres of the sen- 

 tient nerves, which are furnished from point to point in their 

 length Avith nucleated cellular enlargements. It should be 

 stated that these ganglionic enlargements do not exist in the 

 nerves which are distributed to the muscles of the foot. 



