Naturalisation in Extra-Tropical Countries. 245 



has ascertained, that crossing cannot be effected between the oriental 

 and occidental kinds of cotton. A high summer-temperature is 

 needed for a prolific cotton-harvest. Intense heat, under which 

 even maize will suffer, does not injuriously affect cotton, provided 

 the atmosphere is not dry in the extreme. The soil should not be 

 wet, but of a kind that naturally absorbs and retains humidity, 

 without over-saturation. In arid regions it is necessary to irrigate 

 the cotton-plant. Heavy rains at the ripening period are injurious, 

 if not destructive, to the cotton-crop. Dry years produce the best 

 returns, yet aqueous vapor in the air is necessary for the best yield. 

 In colder localities the bolls or capsules continue to ripen, after 

 night-frosts prevent the formation of new ones. Porous soils, rest- 

 ing on limestones and metamorphic rocks, are eminently adapted 

 for cotton-culture. The canebrake-soil of the North-American 

 cotton-regions absorbs ammonia to a prodigious extent. 



Gourliea decorticans, Gillies. 



The Chanar of Argentina and Chili. Bears sweet pleasant fruits, 

 and yields a tough valuable wood [Dr. Lorentz]. As an orchard- 

 tree hitherto insignificant, but it may improve perhaps under cultural 

 care. 



Gracilaria lichenoides, Greville. 



South-Asia, North-Eastern Australia. The "Agar-Agar." An 

 edible seaweed, the mucilage of which has come into preferential 

 use to rear bacteria for microscopic observation. Doubtless, sea- 

 weeds could readily in portable aquaria be transferred from one 

 coast to others. The alg above mentioned can be used medicinally 

 instead of caragaheen. 



Grevillea annulifera, F. v. Mueller. 



West-Australia. A tall bush or small tree, with highly orna- 

 mental flowers. The seeds are comparatively large, of almond-taste, 

 and the fruits produced copiously. The shrub will live in absolute 

 desert-sands, where the other Australian proteaceous Nut-tree, 

 Brabejum (Macdamia) ternifolium, could not exist. Well may we 

 plead, that enlightened statesmanship should lastingly preserve at 

 least on a few chosen spots also in South-Western Australia all the 

 splendid Grevilleas and hundreds of other gay or remarkable plants, 

 quite peculiar to that part of the world, where the endemism of vege- 

 tation is more singularly and strongly concentrated than anywhere 

 else on the globe, unless in South- Africa and California ; so that 

 future generations may also yet be able, to contemplate at least the 

 local remnants of a world of plants as charming as it is diversified 

 and peculiar, before many of its constituents succumb by aggress of 

 herds and flocks altogether. 



