230 



Notes and Memoranda. 



cally rounded in a hollow, to transform it into a magnifying lens. To one 

 extremity of the cylinder a microphotograph is fixed with Canada balsam, and 

 the edges ground by an optical tool to efface the marks of the union. " This is the 

 photomicrographic cylinder, one of the most delightful conquests of science and 

 art. ... If we loot at the plane end of the cylinder we see the picture with great 

 difficulty as a black almost imperceptible point, and M. Dagron was naturally led 

 to do for the second extremity what he had done for the first. He fastened on a 

 second picture with Canada balsam, he rounded the glass in another hollow, and 

 he obtained a cylinder which twice performed the functions of microscope and 

 object holder." In other cases he fixes the picture so that it can only be seen 

 when the glass is held at a particular angle. As the originality of these methods 

 was disputed, and their merit referred to Sir D. Brewster, who gave some similar 

 hints, the Abbe Moigno obtained a letter from that philosopher vindicating M. 

 Dagron' s claims to the invention. 



Claude Bernard on Vascular and Calorific Nerves.— In two papers, 

 which will be found in Comptes Mendtis, M. Bernard describes his " experimental 

 researches on the vascular and calorific nerves of the Great Sympathetic," and thus 

 states certain general conclusions to which he has arrived. " It seems to me proved 

 that the vascular and calorific nerves are special motor nerves. Before mingling 

 with the mixt nerves, these nerves constantly emanate from the ganglia of the 

 Sympathetic, where they may be always found concentrated as in a kind of 

 plexus. These nerves afterwards distribute themselves in a special and exclusive 

 manner to the vessels, and cannot be replaced by ordinary nerves, since, as we 

 have seen, the motor nerves which animate the fibres of a muscle, do not distri- 

 bute themselves to these vessels. Moreover, as I shall hereafter show, the vas- 

 cular and calorific nerves have special physiological properties, and special reactions 

 upon chemical agents." In another place, he observes — " My experiments on the 

 Great Sympathetic of the posterior and anterior limbs, as well as on that of the 

 head, demonstrate that the vascular and calorific nerves are throughout topo- 

 graphically and physiologically independent of the muscular nerves properly so 

 called ; from whence arises this general proposition, that the vascular circulatory 

 apparatus possesses a special vascular motive system, and that the movement of 

 the blood can be accelerated or retarded in the vessels either locally or generally, 

 without any participation of the nervous motor system belonging to muscular 

 movements. The local and functional congestions that periodically occur in 

 certain organs, are examples of this independence of the circulatory movements, 

 and fever furnishes us with a striking pathological example." 



Naudin on Hybrid Plants. — M. Ch. Naudin lays before the French Academy 

 an account of his experiments with Datura Tatula and Stramonium. On crossing, 

 he obtained plants which he calls Stramonio-tatula, and from the seeds of these 

 he obtained offspring of the same sort. From these plants he took seed, and 

 reared twenty-two fresh plants, of which five reproduced the characters of 

 D. Stramonium, nine reproduced those of D. Tatula, and partially returned to 

 the Tatula type, and six were nearer to it than to the hybrid type of the first 

 generation. 



Picrate of Aniline. — We are indebted to Mr. John G. Dale, F.C.S., of 

 Church, near Acrington, for a specimen of this new and interesting substance, 

 which is, as he observes, a very pretty object for the polariscope. He says : " I 

 find the best way to crystallize, is that recommended by Mr. Davies of Warring- 

 ton for his sulphate of copper and magnesia. I make first a cold saturated solu- 

 tion of the salt in alcohol as free from water as possible. Put a few drops on the 

 slide, and dry it quickly over a spirit-lamp. You will by this means get a trans- 

 parent varnish over the glass, from which the salt will crystallize in beautiful 

 disks upon cooling. Sometimes the crystals do not appear with the first applica- 

 tion, owing to the film being too thin ; then it will be necessary to repeat the 

 operation. The crystals should be kept from the air, as they soon get dark 

 coloured." By following the above directions we have obtained beautiful results. 

 Some of the disks have presented exquisite arborescent, rose forms very suggestive 

 of ornamental designs. A pleasing effect is produced by revolving the polarizer, 

 and the selenite stage may be used with advantage. 



