12 NATURAL CONDITIONS OF PLANTS. 
The winter of 1850 — 51 was ushered in by 
some heavy falls of snow, with which I filled my 
Alpine case, giving the plants a perfect rest of 
three or four months, and with a most satisfactory 
result — the Primula marginata, Linncea borealis, 
and other species, flowering much finer than 
usual. Many of these beautiful plants would, I 
am convinced, succeed well, if kept for five or six 
months in an ice-house. 
Plants in hot countries have their periods of 
rest in the dry season. In Egypt the blue water- 
lily obtains rest in a curious way. Mr. Traille, 
the gardener of Ibrahim Pacha, informed me that 
this plant abounds in several of the canals at 
Alexandria, which at certain seasons become dry; 
and the beds of these canals, which quickly 
become burnt as hard as bricks by the action of 
the sun, are then used as carriage roads. When 
the water is again admitted, the plant resumes its 
growth with redoubled vigour. 
On the sandy flats at the Cape of Good Hope 
the heat is so great, that Sir J. E. W, Herschel, 
upon one occasion, cooked a mutton-chop on the 
surface of the burnt soil ;* and this extreme heat, 
coupled with intensity of light, will readily account 
* In the Regio calida-sicca of Brazil, the forests that exist have 
seldom that fulness and lofty growth of those on the coast, and, during 
the dry months, the leaves are deciduous, on which account they are 
