[ 243 ] 
VIII. On the Structure, Relations, and Development of the Nervous and Circulator ij 
Systems, and on the Existence of a Complete Circulation of the Blood in Vessels, 
in Myriapoda and Macrourous Araclinida . — First Series. By George Newport, 
Esq., President of the Entomological Society of London, and Member of the Royal 
College of Surgeons, Corresponding Member of the Philomathic Society of Paris. 
Communicated by P. M. Roget, M.D., Sec. R.S. 8$c. 
Received April 6, — Read April 6, 1843. 
The increasing importance that is daily attached to the study of the comparative 
anatomy of the Invertebrata, and the interest with which every microscopic exami- 
nation of structure is now regarded, as assisting to elucidate the great problems of 
life in the higher animals, have encouraged me through several years to prosecute 
a series of investigations, in the articulated classes, on two of the most important 
portions of the body, — the nervous and circulatory systems. These investigations 
have afforded me, from time to time, some interesting results, part of which, on one 
of these structures, I have already had the honour of communicating to the Royal 
Society. I now propose to communicate the results of my examinations of both these 
structures, and to illustrate their development, and the relations which they bear to 
each other, in some of the principal classes, commencing, in the present paper, with 
the Myriapoda and Arachnida. 
The objects to which my attention has been directed in this paper are three: — 
First, the minute anatomy of the nervous system in the Myriapoda and Macrourous 
Arachnida, more especially with regard to the structure of the cord and its ganglia, 
and the means which these afford us of explaining the physiology of the nervous 
system, and the phenomena of the reflected movements in articulated animals. 
Secondly, to demonstrate the existence of a complete system of circulatory vessels 
in the Myriapoda and Arachnida. Thirdly, to show the identity of the laws that 
regulate the development of the nervous and circulatory systems in these Articulate, 
and their dependence on the changes which take place in the muscular and tegu- 
mentary structures of the body, as I formerly showed in regard to the changes in the 
nervous system of insects*. 
1. Nervous System. — Theory of Development. 
The nervous system of the Myriapoda approaches in the simplicity of its formation 
nearer to that of the Annelida than to any permanent condition in the higher Articu- 
lata, or even to its transitory state in the larvse of insects. In the lowest types of the 
* Philosophical Transactions, 1834. 
2 K 
MDCCCXLIII. 
