Dr. J. H. Gray on Museums and their Uses. 283 
obtained with larvee of a Dyticide (probably of the genus Colym- 
betes) appear to me to prove that in insects the respiratory 
movements are not, as in the Vertebrata, dependent on a special 
focus of innervation. On the contrary, each abdominal ganglion 
is a focus of motory innervation, and takes its part in the per- 
formance of the respiratory act in its totality. It 1s also im- 
portant to remark that, after the section of the nervous chain, 
the isolated action of a ganglion appears to be weaker in pro- 
portion as this ganglion is united with a smaller number of 
other ganglionic elements. 
Thus we see that in this case experiment only confirms what 
anatomy might lead us to foresee; for when we consider the 
distribution of the nervous element in the segments of the thorax 
and abdomen in the Articulata—when we see, in the Crustacea, 
the respiratory apparatus occupying the most diverse positions, 
sometimes on the thorax, sometimes on the abdomen, and re- 
ceiving its nerves from the most different points, it is hardly 
possible to assume that in insects there is a single focus of in- 
nervation for the respiratory function. 
XXXV.—On Museums, their Use and Improvement, and on the 
Acclimatization of Animals ; being the Address delivered to the 
Zoological and Botanical Section of the British Association, at 
the Bath Meeting, by Dr. J. E. Gray, President of the Section. 
BeroreE entering upon the special business for which the Section 
has been called together, viz. the consideration of the Reports to be 
presented upon various zoological and botanical subjects, and the 
reading of the papers submitted by the members, I should wish to 
make a few general observations on some topics which appear to’ me 
to have an important bearing on the science which we study, in the 
hope that they may elicit some observations from the members pre- 
sent. I have always felt that one of the most important uses of the 
Association was the bringing together of so large a body of men 
engaged in kindred pursuits, and the consequent promotion of free 
personal intercourse between those who, not inhabiting the same 
locality or even the same country, were scarcely likely to meet except 
on such an occasion as the present. In such meetings the free 
interchange of thought by means of oral communication is most 
valuable; for it is in this way that facts are most readily brought 
into notice, and opinions most freely canvassed, that truth is most 
effectually elicited, and that erroneous or crude ideas are dissipated, 
corrected, and improved. . 
Some of my predecessors in this office have given a summary 
résumé of the recent progress of science in the departments over 
which I have now the honour to preside, and I had at first thought 
of attempting to follow their example ; but I find myself precluded 
