Academy of Sciences in Paris. 383 



the egg. Among these rhomboids are found a few cubes, and some 

 regular prisms with square bases. The number of these crystals is so 

 considerable, that they may be considered as forming at least half the 

 volume of the egg. The white external points above mentioned 

 indicate the crystals which line the interior surface of the envelope. 

 After these crystals have remained six days between glass plates, 

 their form gradually alters, their angles become rounded, their 

 beautiful white changes to a yellow hue, and they are in a great 

 degree liquefied. These crystals were observed by M. Turpin in an 

 egg laid by a snail on his table, and instantly examined with the micro- 

 scope ; whence he considers it. probable that they are formed in the 

 egg while it is yet in the ovary of the mother, in the same manner as 

 similar crystallizations are formed in the cellular tissues of plants, 

 particularly those of the genus Cactus. MM. Chevreuil and Cordier 

 were requested to verify these remarks, and also to examine whether 

 these crystallizations are peculiar to the garden snail, or whether they 

 are common to every species of the genus Helix, and to the eggs of 

 all the molluscye or molocogoanes ; and also whether similar crystal- 

 lizations could be obtained by submitting the albuminous liquid of 

 the eggs of birds, reptiles, and fishes, to the action of electricity 

 We shall, of course, communicate the result of their investigations. 



MISCELLANEOUS. 



Human Nutrition. On the llth July a letter was read from M. 

 Roulin, a young physician of eminent attainments, both medical and 

 scientific, in which he vindicated the nutritive properties of gelatine, 

 and pointed out the absolute necessity of salt entering into the regimen 

 of animals upon whom the effect of different alimentary substances 

 was to be tried. As a proof of the manner in which animal strength 

 maybe supported, he related the remarkable fact, that in travelling 

 through some forests in Columbia, in 1825, he and his guides, being 

 entirely without provisions, were compelled to eat five pair of sandals 

 (made of untanned leather, softened by the dampness of the forests) 

 and a deer-skin apron, which they roasted and masticated. In the 

 latter operation, two hours were occupied in getting through the third 

 part of the sole of a sandal. This singular aliment supported their 

 strength ; and though the journey, which was to have lasted only 

 two days, occupied fourteen, they arrived at its termination in good 

 health. They occasionally ate the core of the palm-trees, but found 

 that it sustained their strength much less than a piece of the roasted 

 leather. 



New Compressing Pump. On the 18th July a letter was read 

 from M. Thilorier, announcing that M. Perrot had recently applied 

 his new system of compressing gases to an engine of war, by means 

 of which it throws 200 balls per minute. This machine principally 

 differs from that of Perkins by the use of the elastic force of air 

 instead of that of steam, by which a considerable saving of expense 



