CHKM1CAL SCIENCE. 239 



more or less resemblance to this body in composition and structure; espe- 

 cially the concretions of carbonate of lime formed in the bladders of herbivo- 

 rous animals, in which more or less animal matter is always combined with 

 the salt of lime. Numerous concentric layers and a radiated crystalline 

 structure are frequently visible. The organic matter is usually in small 

 proportion, though often sufficient to preserve the original form and structure 

 when the carbonate of lime is removed by acids; occasionally there is more 

 animal matter than in true pearls. 



It is to be regretted that the origin of the cocoa-nut pearl is not certainly 

 known, since neither the chemical nor microscopic characters are sufficient 

 to point out its source and mode of formation. Were the statement of its 

 origin perfectly reliable, it might be regarded as the product of a diseased 

 condition of the nut. The concentric lamination might seem to require a 

 longer time than the rapid growth of the cocoa nut would admit of; but in 

 the case of animal calculi of similar chemical composition, and of such as 

 can be made artificially, these layers, whether resulting from successive 

 depositions or from a process of segregation, may be rapidly formed. A 

 few weeks, and sometimes only a few hours, are sufficient for the production 

 of numerous laminae. 



CELLULOSE DIGESTED BY SHEEP. 



The researches of several German chemists have proved that the cellulose 

 of plants is by no means so indigestible a substance as was at one time sup- 

 posed; but that, on the contrary, it is digested in considerable quantities, by 

 the ruminants at least, especially when a portion of the food of the animal 

 consists of some substance rich in oil. In order to ascertain to what extent 

 the digestibility of cellulose may depend upon its state of aggregation, 

 Sussdorf and A. Stoeckhardt have undertaken a series of experiments, of 

 which only a very brief abstract can be here given. From their results it is 

 evident, that even the most compact kinds of cellulose can be in a great 

 measure digested by sheep. The experiments, commenced in July, 18-39, 

 were upon two wethers, respectively five and six years old. These were fed : 

 first, upon hay alone; second, upon hay and rye straw; third, hay and pop- 

 lar-wood sawdust which had been exhausted with lye in order that the sheep 

 should eat the sawdust, it was found necessary to add to it some rye-bran and 

 a small quantity of salt; fourth, hay and sawdust from pine Avood mixed with 

 bran and salt; fifth, hay, spruce sawdust, bran and salt; sixth, hay, paper- 

 makers' pulp from linen rags and bran. After several unsuccessful attempts to 

 induce the sheep to partake of the pulp when mixed with dry fodder, it was 

 at last given to them in a sort of paste or pap, prepared by mixing bran with 

 water. The experiments were continued until November, with the exception 

 of a short intermission during which the animals were put to pasture, in order 

 that they might recover from the injurious effects probably clue to the 

 resinous matters of the spruce-wood of the fifth series of experiments. 

 The animals, as well as their food, drink and excrements, were weighed every 

 day. The amount of cellulose in the excrements was also daily determined 

 by analysis, the composition of the food ingested having been previously 

 ascertained. It appeared that where the animals were fed, first, with hay 

 (thirty-five pounds per week), sixty to seventy per cent of the cellulose con- 

 tained therein was digested, i. e., it did not appear as such in the solid excre- 

 ments. In this experiment the animals gained seven and a half pounds in 



