54 



mixing of the sulphuric acid with the water, and at the same time 

 the entire liquid contents of the tube will be found to shrink very 

 much in bulk. In like manner a tube in which water has been 

 introduced below, and alcohol above, shows a considerable shrink- 

 age of bulk of its total liquid contents on the mingling of the 

 liquids by inversion, even after they have stood in contact for a 

 year or more, and so it is rendered manifest that the year's time 

 has not sufficed to complete the mixing of the liquids by the process 

 of diffusion. 



On the same evening a paper was read by Dr. Henry Burden, 

 on "The Aquarium." Dr. Burden commenced by remarking 

 that the season was approaching when not a few of the 

 inhabitants of our town, tempted by genial sunshine and re- 

 freshing showers, would seek for a period the charms of a seaside 

 residence, and that, consequently, the present occasion was an 

 appropriate one for the discussion of the subject he had selected. 

 He deplored the indifference shown by the general public for Natural 

 History pursuits, observing that even many who were conversant 

 with the deductions of biology were comparatively ignorant of the 

 inductive substratum upon which that science is based, and earnestly 

 recommended to all such persons the study of those forms of life 

 which abound on nearly every coast. He was convinced that, if 

 examples of a dozen of the principal types of marine organization, 

 at different stages of growth, were carefully examined with reference 

 to development, structure, and function, many of the current 

 doctrines of biology would assume quite a novel aspect to the 

 inquirer. The lecturer here read a list of twelve marine animals, 

 exemplifying as many great groups, which, he stated, were easily 

 procured and of moderate size, would thrive well in confinement, 

 and whose life histories might be readily traced. There was nothing 

 in the task proposed so intrinsically difficult that any well educated 

 person might not confidently undertake it with every prospect of 

 success. The investigation might also be pursued with comfort at 

 all seasons, now that we were enabled by means of a simple con- 

 trivance- — namely, the aquarium — to keep aquatic animals alive and 



