MR. NEWPORT ON THE NERVOUS SYSTEM OF THE SPHINX LIGUSTRI. 415 



US an instance of the commencement of an interesting fact before alluded to, the for- 

 mation of nervous trunks by the approximation and union of many fibres. The series 

 anterior to the fifth ganglion [5. (o)] is now greatly diverging, and the ganglion and 

 nerves are passing forwards and becoming united with it. 



Seven hours after changing [Plate XVI. fig. 24.] there is still an enlargement of the 

 cerebral ganglia, optic nerves, five first ganglia, and their intervening cords. The 

 fourth and fifth have advanced closer together, and the very short cords which con- 

 nect them are so much increased in diameter as to resemble a separate ganglion {x) : 

 the distance between the fifth and sixth is diminished, and all the remaining ganglia 

 are slightly enlarged. The cords between them, just anterior to each ganglion, are also 

 slightly enlarged, and are less irregularly disposed than in the previous stages. The 

 transverse nerves are beginning to assume their temporary ganglionic appearance 

 (o, 0, o) , and the terminal nerves from the last ganglion are enlarging for the supply 

 of the developing organs of generation. 



At twelve hours [Plate XV. fig. 25.] the fifth ganglion, by its coalescence with the 

 cords that united it to the fourth, has assumed a triangular appearance, the broadest 

 part being posteriorly. The transverse series, anterior to the fifth ganglion, which at 

 seven hours was beginning to be united to the nerves from this ganglion, is now so 

 completely joined to them as almost to have disappeared, there being only a triangular 

 elevation upon the anterior part of the ganglion to indicate its previous existence 

 [5. (o)], thus affording us a further proof of the adhesion of contiguous parts, and of 

 the manner in which nervous trunks are formed. 



At eighteen hours [Plate XV. fig. 26.] all the parts have become more concentrated ; 

 the ganglia, cords, and nerves, particularly those to the wings, are more enlarged ; and 

 the transverse nerves, although continuing separate^ give filaments to the nerves from 

 the ganglia, and themselves exhibit at their division more the appearance of ganglia ; 

 while the fourth and fifth ganglia and cords have now so completely coalesced as to 

 appear like an irregular elongated mass. The cords in the abdomen lie more in a 

 direct line, but just anterior to each ganglion are still a little enlarged. 



At twenty-four hours [Plate XV. fig. 27.] the fourth and fifth ganglia have advanced 

 still closer together ; the fifth is slightly larger than the fourth. The cords just before 

 the sixth ganglion are dilated, and the transverse nerves of the thorax are enlarged, 

 keeping pace with, or rather preceding, the development of the respiratory organs. 



At thirty-six hours [Plate XV. fig. 28.] the optic nerves have attained a size almost 

 equal to that of the cerebral ganglia, and after this period become very little larger; and 

 the first suboesophageal ganglion has coalesced with the cerebral ganglia, and forms 

 with them a complete ring around the oesophagus. The fifth ganglion has now de- 

 creased in size, and is smaller than the fourth, while in some specimens the nerves 

 which were given from it now come from the cords immediately behind it, and thereby 

 seem to indicate that part of the nervous substance of the ganglion has been trans- 

 mitted forwards. The sixth ganglion, which at twenty-four hours is decreased in size, 



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