330 ANNUAL KECORD OF SCIENCE AND INDUSTRY. 



soil, in the formation, at a depth of about three feet, of a 

 stony layer, of a brown color and of a moderate thickness, 

 called, locally, allios, and covering a bed of indefinite depth 

 of sand similar to that above it. The presence of organic 

 matter in this allios seems to prove that it has been derived, 

 in a measure at least, from the surface vegetation of the land. 

 In winter and at the commencement of spring the level sur- 

 face of the land is constantly covered, to a greater or less 

 extent, with rain-water. The action of the sun during the 

 warm portion of the year reduces this by evaporation to a' 

 depth of one or two yards in relation to the general level of 

 the swamps and marshes bordering the interior of the chain 

 of downs. A decomposition of the plants of the surface soil, 

 by reason of their long immersion jri the stagnant rain-water, 

 takes place, and the products are carried by this filtering 

 across the upper layer, to the average depth of about one 

 yard. In doing this they appear to cement together, to a 

 certain degree, the sand at this level ; and as the operation 

 has been renewed every year for a long period, a layer of al- 

 lios, more or less compact, is formed, which doubtless will 

 continue to increase. One unfortunate result of this imper- 

 meable subsoil is the development of intermittent fever, which 

 appears to prevail in this region ; and the only way to avoid 

 it is to produce a drainage by digging ditches, and by sink- 

 ing pits in the allios to the depth of about one yard, and 

 breaking holes in its crust, through which the water runs off 

 very rapidly, leaving the surface perfectly dry. To prevent 

 the terrrible conflagrations which would be likely to take 

 place among these forests should they be kept as dry as pro- 

 posed, it is suggested that it will be necessary to divide them 

 up into sections by lines of surface free from vegetation, 

 across which any forest fire would not be transmitted. 3 B, 

 August 4, G32. 



SILK-WORM REARING IN CALIFORNIA. 



Parties in California have for some years found it to their 

 interest to engage in the production and exportation of silk- 

 worms' eggs, for the purpose of supplying Italy and France 

 with healthy worms, as, until quite recently at least, the 

 worms hatched from Californian and Japanese eggs were less 

 liable to the many diseases that had rendered the cultivation 



