1890.] occurring in the NeighbourJwod of Simla. 85 



attacked. Under similar circumstances a few localised patches are also 

 found ; but as a rule the interval is one during which the fungus is 

 comparatively rare. Early in July, after the commencement of the rains, 

 the host puts forth new shoots abundantly, and many of these are then 

 found to be wholly attacked ; localised patches are very rare, and almost 

 entirely absent. The September, towards the end of the rains, localised 

 patches are again formed, and become fairly abundant, though not so 

 abundant as in spring. Lastly, from October to spring the fungus is 

 again rare in both forms ; and, indeed, in the depth of winter (Decem- 

 ber to February) it may be said to be absent. 



The localised patches are found on quite healthy leaves. When 

 quite young they are circular, very conspicuous, especially on the upper 

 leaf surface, from their yellowish green colour, and measure about 5 m.m. 

 in diameter. The edge of the patch above is often surrounded by 

 irregular reddish brown spots. The patches in time increase consider- 

 ably in area. A single leaf may contain from 1 to 8 such patches. 



The leaves of wholly involved shoots are generally covered on their 

 under surfaces with irregular beds of a brownish orange to deeply 

 orange colour, forming diffused blotches, which often in time coalesce, 

 and uniformly cover the whole of the lower leaf surface. A few such 

 blotches sometimes occur on the upper surface also ; but rarely. 



The uredospores are given off in short chains, and there are no 

 paraphyses among them (fig. 2, PI. II). They simply burst through 

 the epidermis, a fray of which may be seen on the margin. The whole 

 depth of the trredo bed is about O'lOO m.m. They are very irregular in 

 size and shape, pale orange or yellowish red in colour, with an epispore 

 finely tuberculated. They measure when fresh and examined in water 

 253 X 21'7/* on an average, varying from 22 x 20 to 30 x 28/*. After 

 lying many hours in water they measure 38 X 30'8/* on an average, 

 varying from 25'2 to 44'1/* in diameter. They germinate in water, but 

 not readily, throwing out a simple' germ tube. In transverse sections 

 three to four ripe spores may generally be seen in a row, with as many 

 immature ones below. It is noteworthy that in fully involved leaves 

 from wholly attacked shoots there is no differentiation of the leaf tissue 

 cells into palisade and spongy cells : the former are, however, quite 

 typical in normal leaves (fig. 2, PI. II). 



The teleutospores are formed beneath the epidermis, which is gradu- 

 ally lifted and disorganised, laying the spores bare. These beds, when 

 just formed, are seen in transverse sections of leaves to be very slightly 

 elevated above the genei-al epidermis . level. The depth of such a bed 

 is about 30/*. When transverse sections of leaves through teleutospore 

 beds are kept in water the spores germinate, throwing out a simple 



