386 Notes and Memoranda. 



common on the hot dry coasts, is very rare on the plateau of Anahuac. Dr. 

 Jourdanet thinks the diminished quantity of oxygen respired may cause this 

 effect. The Mexican plateau does not agree with white races, who become weak, 

 and would disappear if not constantly renewed from Europe. The aboriginal 

 races disappear gradually in contact with ciyilizatiorj, but the half-breeds gradu- 

 ally increase, and seem able to resist the climate. The Swiss Association of 

 Science has determined to investigate the effect of altitude on pulmonary con- 

 sumption in Switzerland, and is about to issue circulars to medical practitioners in 

 the high villages. 



Camera Obscuea foe the Miceoscope. — Mr. E. Hinchcliffe writes to say 

 that he takes a strong box, about a foot square, blackens it inside, and bores a 

 hole at the top, through which he places the tube of his microscope inverted. 

 The foot of his microscope is fixed to a square board, and a four-legged stand is 

 placed on the top of the box for this board to rest upon. An ordinary lamp and 

 the concave mirror he finds to give sufficient light, and the image is received and 

 traced on a sheet of paper placed at a convenient distance from the eye-piece. A 

 correspondent some time ago sent us a communication recommending the conver- 

 sion of the camera Ittcida^ into a camera obscura, by turning the prism so that 

 the image, instead of being reflected into the eye, was thrown down on paper. 

 The objection to such plans is that they are only applicable to objects which are 

 tolerably easy to draw, and which are displayed with ease under slight magnifica- 

 tions. Eine markings or delicate structures seen with high powers, and requiring 

 careful illumination to bring them out, could not be dealt with in this manner. 



The Habits op the Caplpn. — In the Transactions of the Nova Scotia Insti- 

 tute of Natural Science, part i., vol. ii., is an interesting paper by Captain Hardy, 

 on the fish called the caplin, which has been considered of the salmon family, of 

 which it is the smallest member, being about seven inches long. Its scientific 

 name is Mallotus villosus. It swarms on the coasts of Norway, Lapland, Iceland, 

 Greenland, Newfoundland, etc. In the breeding season, but Captain Hardy thinks 

 not at other times, the males have elevated ridges at their sides, composed of soft 

 tumid elongated scales, having the appearance of rainbow-coloured velvet. The 

 female is quite smooth. Captain Hardy has collected proofs of the statements 

 originally made by Chappell, that at the breeding season the females, accompanied 

 by a male on each side, rush on the sands, and the soft ridges of the males are em- 

 ployed in gently squeezing the female to expel the eggs. The caplin is considered 

 essential to the cod fisheries, as no other Jknown bait will tempt the cod in their 

 swarming season. Captain Hardy is of opinion that the reckless destruction of the 

 caplin for manure and other purposes will, if continued, ultimately ruin the 

 fishery. 



Habits op the Stoem Peteel. — In the same publication we find observations 

 on this bird by the Eev. John Ambrose. He visited the breeding places of the 

 petrels on Green Island, about ten miles off land, in the mouth of Chester Bay. 

 The petrels exhale a disagreeable odour, which he perceived at a distance of two 

 miles from the island, and which he tells us a " gentle air " often carries to 

 " Peggy's Cave," a distance of fifteen miles. The birds are nocturnal in that 

 locality, and only seen abroad in day time in dull foggy weather. He landed at 

 sunrise, and found them all in their holes underground, twittering like the 

 squeaking of mice. " On taking a petrel out of its nest, it would not at first, on 

 being set down, attempt to fly ; but would endeavour to dig and shuffle its way 

 into one of the broken holes." The nests are made in the angles of galleries, 

 about six inches below the surface and parallel with it. Each nest has at least two 

 ways of access to it. It is formed with a little dry grass, and kept very clean. 

 The petrel uses its beak in these excavations like a pick-axe, and throws the loose 

 earth behind it by kicking alternately with each foot. Mr. Anderson is convinced 

 that the habit of the petrels of that district is to spend December, Janua.y, and 

 Eebruary, somewhere more south, and to pass the greater part of that time ut Bea, 

 near the Gulf Stream. They appear in their burrows on Green Island about the 

 middle or latter part of April. 



