182 CHAPTER OF VARIETIES. 



probable, that the fluids used were filtered, and their colouring particles 

 thrown back, by the minute openings of the air cavities. That difficulty 

 may be avoided by filling the air cavities successively with two diffe- 

 rent fluids ; such as prussiate of potass and sulphate of iron in solution. 

 Assuming these air cavities to perform that necessary function in 

 vegetable, which is performed by the lungs in animal, life j that is, the 

 aeration of the circulating fluids, their number and capacity must be in 

 proportion to the quantity of fluids circulated. The sap or circulating 

 fluid, is more abundant in young trees than in old ones, and in 

 fresh shoots than in matured ones. As regards the trees themselves, 

 the necessary supply of aeration may be provided for by an 

 increased foliage, as we find to be the case with respect to young 

 trees. But with respect to branches when the same leaves remain on 

 the same branch during a whole summer, the varying supply cannot 

 thus be provided for, since, while the degree of succulency and rate of 

 growth diminish, the aerating surface of the leaves increases. Another 

 expedient appears therefore to be adopted. Take the young shoot of 

 a vine, with its newly pruned leaves. Both sides of each leaf are 

 alike pale-coloured and covered with air cavities. The quantity of 

 aerating surface is thus increased by being extended to both sides of 

 the leaf. As the leaf grows, and the branch on which it stands is 

 matured, the upper surface loses its air cavities, which have become no 

 longer necessary. W. B. 20th March, 1833. 



ATTACK OF SPARROWS ON A MOUSE. In the summer of 1831, one 

 of the residents of the Temple turned a mouse loose in the open grand 

 space, and the little intruder had no sooner made his appearance, than 

 he was simultaneously attacked by the sparrows, which commenced so 

 deadly an attack on him that he ran in all directions, endeavouring to 

 escape their fury, and leaped up in the air in great agony, in vain, for 

 the persecution abated not until the little sufferer ceased to exist. 

 VERITAS, March 6, 1833. 



SOCIALITY OF A RAT WITH A YOUNG CAT. We have frequently 

 opportunities of observing the association of animals, which in a state 

 of nature exist in hostility to each other ; but this is generally the 

 result of education. It may therefore appear the more surprising, that 

 without any apparent cause for such an act of friendship, our cat (a 

 young one) should have permitted a rat to partake of her morning's 

 breakfast. During the last summer, when our cats were lapping their 

 morning's portion of bread and milk, a rat was frequently observed to 



