406 MR. NEWPORT ON THE NERVOUS SYSTEM OP THE SPHINX LIGUSTRI. 



in the higher animals, must long ago have taught us. That since the laws of nature 

 are simple and uniform, the same principle exists through the whole series of 

 animated beings ; — that however altered in arrangement or appearance in different 

 parts of the series, structures corresponding to those which are endowed with especial 

 properties in Man, and his immediate affinities, exist in every organized creature 

 having the powers of locomotion and sensation. Yet however certain this principle 

 must have appeared to every reflecting mind, we have not until recently been able to 

 distinguish in invertebrated animals the particular structures from one another, and 

 to show their analogy with similar structures of the nervous system in the vertebrated. 

 Some, therefore, have imagined that the gangliated cords of the Invertehrata are sim- 

 ple structures, communicating both sensation and motion. This, however, I shall 

 endeavour to show is not the case. 



It was during the early part of the summer of 1833 that I first had an opportunity 

 of conversing with Sir Charles Bell respecting the nervous system of insects, when 

 he suggested a closer examination of the cords than I had then made, to ascertain 

 whether a double nervous column, one portion for sensation, and the other for motion, 

 exists in the Invertehrata, as in the higher animals. He at the same time pointed out 

 one of the Crustacea, the Lobster {Astacus marinus. Leach), as perhaps the most 

 eligible for the inquiry. At that time I had no hopes of succeeding in demonstrating 

 the parts by dissection, although I believed they really did exist. In the month of 

 August, after many dissections and examinations of the animal in its recent state, I 

 began first to hope for success ; and in the beginning of September completed a pre- 

 paration of the nervous system of the Lobster, which I still possess, that appeared to 

 show the two motor and sensitive columns, and I immediately communicated the cir- 

 cumstance to my friend Dr. Marshall Hall. Early in October a second preparation 

 was completed, which showed these columns far more distinctly than the first. Fearing 

 the possibility of mistake, I showed the preparation to Dr. Hall, a few weeks after- 

 wards to Professor Grant, and many others : it is now in the possession of Sir 

 Charles Bell. 



The nervous system of Crustacea has been examined by many anatomists, Edwards, 

 Carus, Home, and others. In the Lobster it is formed upon the same general plan as 

 that of insects. It consists of two longitudinal cords, corresponding to the two halves 

 of the body, united at certain distances by ganglia [Plate XVII. fig. 40. (1 to 14.)]. 

 These cords are double, each being composed of two tracts, lying one over the other 

 [fig. 42. {u, v)'], analogous to the motor and sensitive tracts in the spinal column of Ver- 

 tehrata. These tracts, however, are not readily distinguished until after the cords have 

 been kept for a short time in alcohol, when they become very evident even to the naked 

 eye. The ganglia [figg. 40, 41, 42. {u, v)'\ are fourteen in number, one cerebral (a), and 

 thirteen suboesophageal (c, d). Seven of these are thoracic (c), and the remainder are 

 post-abdominal or caudal ganglia (d). They all belong entirely to the sensitive tract, 

 which lies nearest to the under or exterior surface of the animal. The tracts are in 



