210 ANNUAL OF SCIENTIFIC DISCOVERY. 



eighteen days. Second, with hay fourteen pounds, and straw seven pounds 

 (per week), forty to fifty per cent of the cellulose of the straw was digested; 

 the animals having lost two and a half pounds in eleven days. Third, with 

 hay ten and a half pounds, poplar sawdust five and a quarter pounds, bran 

 seven pounds (per week), forty-five to fifty per cent of the cellulose of the 

 poplar-wood was digested; the animals having gained two and a half 

 pounds in thirteen days. Fourth, with hay ten and a half pounds, pine-wood 

 sawdust seven pounds, bran ten and a half pounds (per week), thirty to forty 

 per cent of the cellulose of the pine-wood was digested ; the animals having 

 gained ten pounds in twenty-four days. Fifth, with hay nine and a half 

 pounds, paper-makers' pulp seven pounds, bran fourteen pounds (per week), 

 eighty per cent of the cellulose of the paper pulp was digested; the animals 

 having gained seven pounds in as many days. 



These experiments are to be continued, and more particularly with a view 

 of ascertaining whether any nourishing effect is to be attributed to the cellu- 

 lose. Stceckhardt's Chemisclier Ackersman, I860, Xo. 1, p. 51. 



CHITINE. 



M. Peligot, describing some investigations on the chemistry of the skin of 

 the silk-worm in the Annales de Chimie et de Physique, states the discovery of 

 cellulose in the chitine which it contains. He obtained similar results from 

 the chitine of the lobster, and thinks it probable that chitine is never a single 

 substance, but a mixture of two substances, one non-nitrogenous cellulose 

 and the other nitrogenous, belonging to the class of albumenoid or protein 

 compounds. He says that a mixture of two parts of protein and one of cel- 

 lulose would have the composition which he considers to belong to the skin 

 of silk-worms. Cellulose is the proximate principle of which the vegetable 

 cell membranes of plants is composed, and, according to the Micrographic 

 Dictionary, is found in the mantle of the Tunicata. Should M. Peligot's 

 views be found correct, the relations between the animal and vegetable king- 

 doms will appear stronger, as chitine is the horny substance which gives 

 firmness to the shells and skins of the crustaceans, spiders, and insects. M. 

 Peligot thus sums up the philosophy of his researches : " The exterior envelop 

 of animals and plants, whether it be more or less resisting, is composed 

 of two substances, cellulose and protein, cellulose, which exists in vegeta- 

 bles and the inferior animals; cellulose and protein, Avhich exist in animals 

 of a higher organization; and of protein alone, which forms the tissues of 

 the vertebrate class." 



ON THE PRESENCE OF ARSENIC IN PLANTS USED FOR FOOD. 



It will be recollected that Professor Davy, of Dublin, last year reported the 

 results of some experiments which went to show that some plants might with 

 impunity be watered even with a saturated aqueous solution of arsenious 

 acid; that the plants took up this arsenic and accumulated it in their tissues, 

 to such an extent that traces of this metal were discoverable in the bodies of 

 animals fed upon vegetables so treated. These astonishing results naturally 

 excited inquiry. They have now been contradicted in a late number of the 

 Pharmaceutical Journal, by Mr. Ogston, an analytical and agricultural chem- 

 ist, formerly a pupil of Professor Graham. Mr. Ogston finds that, on watering 

 the ground around Uie roots of sorae vigorous cabbage-plants, some months 



