GROWTH AND FOOD OF ANIMALS. 151 



alteration was produced upon the tubes of tin, but when made 

 of lead, they were evidently compressed ajid flattened. When 

 unbroken grains and seeds were inclosed in perforated tubes 

 and thrust into their stomachs, no change whatever was pro- 

 duced ; no solution appeared to have taken place. But when 

 the same substances were bruised into a coarse flour, so as to 

 get rid of their husks, a very sensible diminution of their bulk 

 took place, and on being several times introduced, they were 

 finally entirely dissolved. Wheat and beans, when eaten vol- 

 untarily by the crow, offered similar phenomena. Before 

 swallowing, the animal set them under its feet, and broke 

 them in pieces by repeated strokes of its beak; and then they 

 were very well digested. But when the same seeds were 

 swallowed entire, they were generally vomited up, or voided 

 unaltered. Similar experiments were made with French 

 beans, peas, nut-kernels, bread-apples, and different kinds 

 of flesh and fish ; and corresponding results were obtained.' 



3. Spallanzani finished his experiments on digestion with 

 those animals which have thin membranous stomachs, as man, 

 quadrupeds, fishes, reptiles, and some birds. In these, the 

 coats of the stomach seemed to have little or no mechanical 

 action upon their contents ; the gastric juice being fully suf- 

 ficient to break down the food and reduce it to a pulp. 



With regard to man, Dr. Stevens, in an Inaugural Disser- 

 tation concerning digestion, published at Edinburgh, in the 

 year 1777, made several experiments upon a German, who 

 gained a miserable livelihood by swallowing stones for the 

 amusement of the people. He began this strange practice at 

 the age of seven, and had at that time continued it about 

 twenty years. He swallowed six or eight stones at a time, some 

 of them as large as a pigeon's egg, and passed them in the nat- 

 ural way. Dr. Stevens thought this poor man would be an ex- 

 cellent subject for ascertaining the solvent power of the gastric 

 juice in the human stomach. The Doctor, accordingly, made 

 use of him for this purpose. He made the German swallow a 

 hollow silver sphere, divided into two cavities by a partition, 

 and perforated with a great number of holes, capable of ad- 

 mitting an ordinary needle. Into one of these cavities he put 

 four scruples and a half of raw beef, and into the other five 

 scruples of raw bleak. In twenty-one hours the sphere was 

 voided, when the beef had lost a scruple and a half, and the 

 fish two scruples. A few days afterwards, the German svvalr 

 lowed the same sphere, which contained, in one cavity, four 

 scruples and four grains of raw, and, in the other, four scruples 





>c.J> 



