194 



PART III. 



MISCELLANEOUS INTELLIGENCE. 



Art. I. Natural History in Foreign Countries* 



FRANCE. 



JRepsoducTION of Leeches. — It has been found by M. Pallas^ that after 

 leeches have been used for medicinal purposes, they are most reproductive. 

 He puts them into a box with argillaceous earth, six inches deep, at any 

 time from the middle of August till the end of September. In five months 

 cocoons will be found, each containing twelve individuals. The cocoons 

 are, on the outside, light, porous, and woolly, to keep out moisture and regu- 

 late the temperature; on the inside they are fibrous and dense, enclosing a 

 thin multilocular pellicle, which contains germs. — Bulletin des Sciences No- 

 turelles. 



As the medicinal leech is a native of Britain, and by no means uncommon 

 in lakes and pools in marshes, the preceding experiments of M. Pallas might, 

 perhaps, be turned to profitable account in the breeding of animals in such 

 extensive demand as leeches. The greater number, it may be supposed, of 

 the leeches which have been used, die soon afterwards; but if they were 

 employed as breeders, and since M. Pallas says they are the best breeders, 

 it would be turning a loss into a considerable profit. — J. R, 



Nature of Vegetation at dif event Epochs of the Crust of the Globe. — 

 M. Adolphe Brongniart has published an interesting paper upon this subject 

 in the Annates des Sciences Hist. Nat. for November, in which he divides 

 the time of the formations into four periods ; viz. — 



1. The immense numerical predominance of vascular Cryptogamia, that 

 is to say, 2<'ilices, Characeas, and Lycopodiaceae, and the great developement 

 of these plants, are the essential characteristics of the first period, 



2. The numerical equality of vascular Cryptogamia, of gymnospermatic 

 Phanerogamia represented by the Coniferae and Monocotyledones, as well 

 as the least developement of the vegetables of the first of these classes, 

 appear to be the essential marks of the second period. 



3. The third period is particularly distinguished by the predominance of 

 gymnospermatic Phanerogamia, and particularly of Cycadeae ; the vascular 

 Cryptogamia hold the second rank, and then an inconsiderable number of 

 Monocotyledones succeed. 



4. Lastly, the fourth period presents us with the vegetables of all the 

 classes at present existing ; among which, as at this epoch, Dicotyl^dones 

 are by far the most numerous ; then Monocotyledones, gymnospermatic 

 Phanerogamia, and, last of all, Cryptogamia and Agamia. The following 

 Tables, however, will exhibit these interesting views more distinctly : —. 



