75 



This latter fungus and Peridermium giganteum, as far as my observa- 

 tion goes, are usually found on their respective hosts only when they grow 

 in the same place; and when one of these host-plants does not occur, these 

 two parasites are also absent. 



Thus for example, in an extensive pine plantations of Miono-matsa- 

 bara in the province of Suruga where no deciduous quereus is found, I 

 could not find any pine having excrescences caused by the parasitic action 

 of Peridermium giganteum. 



On the other hand in Kashima-gori in the province of Hidachi, where 

 the plantations of these species of host plants stand side by side, we see 

 a luxuriant growth of both of these parasitic fungi. 



From these facts and from similar instances in Europe, I thought it 

 highly probable that these two forms of fungi must have genetic connection 

 and belong to one and the same species, and was induced to make a 

 culture experiment on this subject. 



I conducted the experiment during the last two years (1897-1898)° in 

 the Botanical Laboratory of the Agricultural College of the Imperial Univer- 

 sity and obtained a positive result. 



Unlike other species of Peridermium our present Bpecies excites the 

 growth of the cambium of the attacked portion very much, and causes the 

 abnormal increase of the wood and bark, so that one year's growth corres- 

 ponds to 3 or 4 year's growth of the healthy portion. 



This fungus at first attacks young branches, stems, or even exposed 

 portions of roots, and produces in the first year a small hemispherical 

 swelling of the size of a hemp-seed. 



This small swelling or excrescence gradually increases in size year by 

 year, and after many years' growth it assumes a spherical form, sometimes 

 attaining an enormous size of half a meter or more in diameter. 



But as the wood and cortex of the diseased portions are softer and 

 not well developed, they are liable to be killed by severe cold and also liable 

 to be attacked by insects and other fungi before they attain such a 

 large size. 



In the latter case, the interior of the excrescence commences to decay 

 and gradually becomes hollow ; and at last it is broken by the action of a 

 violent wind or by the pressure of a heavy snow. 



The mycelium which extends through the cortical parenchyma and is 

 formed of a thick matrix of an interlaced hyphse, completely fills the 



3) This year also I am continuing the experiment and have already seen the 

 uredo- layer. 



