although the lower leaves may have become 'completely wilted and defoliated. 



If the surrounding conditions are favourable to the growth of the fungus in 

 September, the disease spreads again actively. In this case, the spots are not so 

 angular, as in those in the early summer, and are more in number and smaller in 

 shape. In the autumn, it is difficult to distinguish this disease, as the diseased 

 leaves are generally attacked by many saprophytic fungi. The disease may not 

 cause a great loss of the crop; but it may interfere with the general productive- 

 ness by diminishing its assimilating surface and sometimes by causing defoliation. 



Causal Fungus. 



A section through the diseased spot shows the hyphae to be ramifying in the 

 tissue of the leaf, whose chloroplastids are destroyed. The hyphae are 2-4 /j. in 

 width. The pycnidia are formed under the epidermis and immersed into the 

 tissue at the both sides of the leaf (mostly on the upperside). They are globose 

 or conico-globose and measure 44-100 /u (commonly 60—70 //) in diameter. The 

 wall of the pycnidium is rather thin, membranaceous and brown or dark brown in 

 color. It has a short round papilla which is at first covered, then erumpent with 

 a comparatively large mouth. 



The spores are filiform, straight or mostly curved irregularly, smooth, hj'aline 

 and occasionally guttulate. When the spores are stained with iodine solution, it 

 will be clearly observed that they consist of one to three, rarely of four cells. 

 When it is mounted in water or potash, these septa may often be overlooked. 

 Their measurement are 21.0-52.5 x i. 4-2.1 fj.. The conidiophores are very short 

 and I could not examine them exactly. Placed in a drop of water or nutritient 

 media, the spores swell at first, showing the septa clearly, and then germinate 

 within 24-50 hours in the room temperature, throwing out one or two germ-tubes 

 from each cell at or near the septa or also at the ends of the spores. The ger- 

 minating hyphae are hyaline and about 2—3 ti in width. The septation and 

 branching then take place. 



From the morphological characters of the spores and pycnidia, we may easily 

 recognize our present fungus to be a species of Septoria. Up to the present time, 

 I have not yet been able to obtain its ascosporous stage. According to the des- 

 criiDtion, Septoria SOJina Thilm., which is tlie only species known to be parasitic 

 on the leaves of Glycine hispida, is quite different from the present species in 

 many points, especiallx' in the measurement of the spores. The important charac- 



