Notes. 
563 
the root. Those tubers which are not attacked while still very young, 
but which have already begun to fill with starch, may offer considerable 
resistance to the invasion of the fungus ; but eventually the vascular 
strands diverging from the point of attachment to the rhizome exhibit 
the tell-tale foxy-red or yellowish-brown colour, and in many cases the 
ripened tubers are to all appearance sound, except for microscopic 
reddish spots just at the points of entry of these bundles. 
During the winter the stored potatoes, with the fungus thus just 
lurking in them at the morphological base (the so-called heel) of the 
tuber, may undergo little change to all appearance if gathered and 
stored dry . 
But if wet, various kinds of rot may supervene, owing to the 
subsequent invasion of various micrococci, bacteria, fungi, &c., following 
the lines of weakness opened up by the fungus in question, and living 
as saprophytes on the stored reserves. 
In some cases even apparently dry tubers may undergo a curious 
rot — dry-rot — owing to the ravages of a particular bacterium or mould, 
perhaps more than one, which finds sufficient moisture for its 
purposes. 
The principal point is that the fungus I have especially studied 
leads the way for these purely saprophytic anaerobic and aerobic forms 
into the tuber: once in the mature tuber, its progress is necessarily 
slow until the reserves move in the spring. 
During the past winter I gave to Miss Dawson, who is working at 
such subjects in my laboratory, some of the tubers saved from plants 
attacked with this disease, to investigate the various fungal forms 
lurking in the diseased tubers. Her investigations are not yet com- 
pleted, but enough has been accomplished to convince us that after 
the fungus in question has opened up the way into the tuber, all sorts 
of bacteria and fungi can make their way down the destroyed vascular 
strands, and reappear in spring, when the tubers are replanted. 
But this is not all. The evidence shows that the fungus in question, 
once in the tuber, leads a dormant life during the early part of the 
winter, but gradually invades the new sprouts as they slowly appear in 
the early spring, and that the parasite is actually replanted by the farmer 
or gardener, when restocking the ground, in his new ‘ sets! 
If we reflect that the tuber is really a bud, there is nothing especially 
strange in this phenomenon ; the fungus enters the base of the bud in 
autumn, and takes some months to traverse its dormant tissues during 
