Naturalisation in Extra-Tropical Countries. 315 



calculations of this kind are explained by differences in clime, soil, 

 attention, treatment and also rate of labour. 



A very palatable fruit is obtained from a variety cultivated in 

 Beloochistan and Afghanistan. The white-fruited tree was found 

 apparently wild by Dr. A. v. Regel, at Taschkend and Tutkaul ; the 

 stems there were 7 feet thick. 



The results of Mr. Brady's experience on the varieties of Morus 

 alba are as follows : In the normal form the fruits are white with a 

 purplish tinge more or less deep ; the bark is pale ; the leaf is also 

 of a pale hue, not very early, nor very tender, nor very abundant. 

 It may be grown on moist ground, so long as such is drained, or it 

 will live even on poor, loose, gravelly soil, bordering on running 

 water. The Cevennes-variety is a free grower, affords a large 

 quantity of leaves, though of rather thick consistence ; all varieties 

 of the Morus-Bombyx like these leaves, whether young or old ; it is 

 also called the Rose-leaved variety ; the silk, which it yields, is sub- 

 stantial in quantity and also good in quality ; does best on rich dry 

 slopes. The bushy Indian variety has a fine leaf of a beautiful green, 

 which, though light in weight, is abundantly produced ; it can be 

 cut back to the stem three or four times a year ; the leaves are flat, 

 long and pointed, possess a fine aroma, and are relished by every 

 variety of the ordinary silk-insect, though all do not thrive equally 

 well on it ; the silk derived from this variety is excellent, but not 

 always so heavy in quantity as that produced from the rosy variety ; 

 it prefers rich, low-lying bottoms, is a greedy feeder, but may thus be 

 made to cover an extraordinary breadth of alluvial or manured land 

 in a marvellously short space of time. At Sydney Mr. Brady can 

 provide leaves from this Indian variety all through the year by the 

 removal of cuttings, which will strike their roots almost at any 

 season ; it also ripens seeds readily, and should be kept at bush-size ; 

 it requires naturally less space than the other kinds. A fourth 

 variety comes from North-China ; it has heart-shaped, flat, thickish 

 leaves, which form very good food for the silk-worm. Mr. Brady, as 

 well as Mr. Martelli, recommend very particularly the variety passing 

 under the name of Morus multicaulis for the worms in their earliest 

 stages. The former recommends the Cape-variety also ; the latter 

 wishes likewise the variety called Morus Morettiana to be used on 

 account of its succulent nutritious foliage, so well adapted for the 

 insect, while yet very young, and also on account of producing the 

 largest amount of food within the shortest time. This Manilla- 

 variety, above mentioned as Morus multicaulis, comes into bearing 

 several weeks earlier than most other sorts, and should therefore be 

 at hand for early hatched worms. An excellent phytological exposi- 

 tion of the numerous varieties of the White Mulberry-tree is given in 

 De Candolle's prodromus XVII. 238-245 (1873), by Bureau. 



The Muscardine-disease is produced by Botrytis Bassiana, while 

 the still more terrible Pebrine-disease is caused by the minute 

 Nosema bombycis (Naegeli). On the Pebrine Pasteur's researches 

 since 1865 have shed much light. The silk-worm may become 



