410 MR. NEWPORT ON THE NERVOUS SYSTEM OF THE SPHINX LIGUSTRI. 



body, and consist each of a column of fibres, which at certain distances inclose a 

 nodule of granulated, opake, grey matter, which constitutes a chief part of the gan- 

 glion. A few fibres of the sensitive column pass on that side of the nodule which lies 

 to the median line of the body of the insect ; while the larger portion of the column 

 passes on the outer side of the nodule, from which the nerves are given off, and the 

 two portions of the column uniting again behind the nodule thus constitute a gan- 

 glion. As the development of the nervous system proceeds, the ganglion thus formed 

 in the sensitive column of one cord is closely applied to, and firmly united in, the 

 median line, with a corresponding ganglion in the sensitive column of the other ; 

 and the two thus combined form a double ganglion of the spinal or symmetrical 

 system. The motor column [Plate XVI. fig. 35. (5) J, consisting entirely of a series 

 of longitudinal fibres, giving oflT nerves at certain distances, lies upon, and is closely 

 approximated to the sensitive (a), which it very nearly equals in diameter, and is only 

 clearly distinguished from it while passing over the ganglia, and by a line which runs 

 along the sides of each cord. The motor nerves are given off from the column at the 

 anterior margin of each ganglion (A), along which they pass diagonally outwards, until 

 they reach the nerve from the ganglion (/), with which they immediately unite. In 

 the caudal ganglion of the Sphinx [fig. 36.], which at this period consists of two 

 double ganglia, the motor column (b), after being thus distributed to the first, passes 

 on to the next, and terminates in each half of the column dividing upon the middle 

 of the ganglion into two portions {b b}, that unite with the terminal nerves which are 

 given to the rectum and generative organs. In the thoracic part of the insect, the 

 double-rooted nerves to the wings are formed, first by the anterior root, which is 

 derived entirely from the motor column, and next by the posterior, which is formed 

 by one part from the motor and one from a ganglion of the sensitive column. In 

 addition to these, the nerves of the wing receive several large nerves from the trans- 

 verse or respiratory series, the anatomy of which has been described in a former 

 part of this Paper*. 



In the Papilio urticoe, Linn. [fig. 37.], and P. lo, Linn., the ganglia are exceedingly 

 large compared with the size of the cords. When examined with a very strong light, 

 the motor column may be seen from the under surface of the cords through the gan- 

 glia quite distinct from the sensitive, and it continues so along the sides of the cords 

 into the nerves of the wings. This is an interesting fact, on account of the wings 

 being supplied with nerves in Papilio, Linn., directly from the cords, and not as in 

 Sphinx from the cords and ganglia. The motor nerves pass around the exterior of 

 the ganglia, and the column itself passes over them, exactly the same as in other 

 Articuvata. 



We have thus a series of facts which distinctly show the existence of a nervous 

 system analogous to that of vertebrated animals through all the higher Articulata ; 

 and it cannot be doubted that the same structure exists throughout all the articu- 



* Page 402. 



