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somewhat curved and septate (jointed), whereas those 

 of the Phytophthora are colourless and not septate. 

 The conidia are oblong pointed, and divided by trans- 

 verse and longitudinal septa, while in the phytoph- 

 thora they are colourless and egg-shaped. 



At present the full life-history of the fungus is not 

 known, but it is probably an early form of some 

 species of sphseria not yet recognised. The attack is 

 made on the leaves, and does not reach the tubers, so 

 it is assumed that the conidia rest on the decaying 

 leaves and stems of the plants, or on the ground. 

 The leaves, when attacked, gradually shrivel and die, 

 leaving the stem bare ; consequently the plant dies, or, 

 in less severe attacks, loses its vigour and produces a 

 proportionately small crop. 



-Although the life-history is not satisfactorily traced, 

 it is known that spraying with the Bordeaux mixture 

 prevents and cures the disease. The method adopted 

 for preventing the ordinary potato disease is equally 

 suitable in the case of the Macrosporium attack ; in 

 fact, when using the mixture to check the Phytoph- 

 tbora, there is no need to fear the Macrosporium. 



The smut of potatoes Tuberania scabies is caused 

 by an olive-green or brownish fungus, which attacks 

 the haulm, causing blotches to appear on the skin ; 

 these blotches sometimes develop to such an extent 

 as to merge, so that in time the whole of the skin is 

 discoloured. In course of time the fungus, which has 

 hitherto lived under the skin, bursts through, and 

 gives off olive-green spores. The tuber itself becomes 



