He also inquired whether tadpoles and leeches would live when kept only in distilled water, with the admission of air. For example, he placed twelve leeches in two gallons of distilled water, They weighed, in all, twelve scruples. In three months, two had died, but the remaining ten weighed twelve scruples, showing that they had _grown_. He next inquired whether vegetables, grown in air and distilled water, would admit of further conversion into the structure of animals; and, for this purpose, he fed rabbits on vegetables so reared. His rabbits appear to have eaten about six plates at a meal of young cabbages thus reared on flannel wetted with distilled water. He also experimented on eggs, both before and at the time of incubation. He wished to ascertain the quantity of lime in the chicken and the egg, respectively; and whether any of the lime was absorbed from the shell, which it appeared not to be. It is curious to observe the time and labour he gave to these experiments; they evince a very perfect knowledge of the chemistry necessary; whilst the circumstances calculated to interfere with or obscure the conclusions from them are judiciously and clearly stated. Many of his remarks, as well as the ingenious suggestions with which they are interspersed, exemplify the caution with which he reasoned. In speaking of his experiments on leeches and tadpoles, many of which latter had become perfectly developed frogs, he says: "The experiments which I made on this plan (in vessels of distilled water, covered with linen) were made in the summer, when to prevent vegetation was impossible; and, on the other hand, when the vessels were covered over, even leeches died. In the winter, vegetation might cease; but then the torpid state of the animals would render the experiments inconclusive." He reduced an equal number of eggs and chickens (at the time of incubation) to ashes; sometimes in crucibles, sometimes in retorts. On the ashes he poured some distilled water, and ascertained the salts (as lime, &c.) contained in them. In some experiments, the quantity of these found in the ashes of the chickens greatly exceeded that found in the ashes of the eggs. In other experiments, the quantities were equal. In some of his experiments, after using the best chemical tests for detecting iron, lime, and the salts, and then washing the residue with distilled water, he burnt it in a crucible, and found more lime and iron; on which he makes the following remarks, which suggest what we apprehend, even at this time, is a very necessary caution: