ADDENDA 569 



the sphere. The secondary spheres may behave as secondary 

 sori, and budding may be continued until the ultimate spore 

 form is reached. The spores give rise to exceedingly small 

 swarm spores. The organism is best seen in a narrow pink, 

 purple, or yellowish zone at the base of the eye, in the tissue 

 surrounding the old stalk of the tuber, and in the wound 

 cambium which surrounds the brown affected areas in the 

 flesh. The most conspicuous objects are the pink or 

 purplish thick-walled sphere-sori, located amongst the starch 

 grains. 



It is suggested that the organism be provisionally regarded 

 as a Chytridiaceous fungus of generic rank. 



The fuller account of this mysterious body will probably 

 clear up the uncertainties that exist at present. It is to be 

 regretted that the presence of the organism is not said to be 

 present in the diseased portions of the tuber. 



Home, A. S., Annal. My col. , 7, p. 286 (1909). 



'Sprain' of potato tubers. Several examples of potatoes 

 said to show the disease called 'sprain' in the north of 

 England and Scotland, have at various times been sent to 

 Kew. The appearance is so different in the various examples 

 that it is impossible to draw up a satisfactory diagnosis. The 

 most constant feature perhaps is the presence of rust-coloured 

 patches scattered in the flesh. Very frequently the flesh also 

 presents a water-logged appearance. These rusty spots 

 closely resemble those present in the tubers of potatoes show- 

 ing what is termed ' internal disease ' in the south of England. 

 In both instances the brown spots possess many features in 

 common with those present in the disease of apples known as 

 'bitter-pit.' In some instances mycelium can be detected in 

 the brown patches, and in such instances, when the slices of 

 potato are placed under suitable conditions, 'winter-rot,' 

 caused by Nectria solani, invariably makes its appearance. 

 In other instances, however, no mycelium can be found, and 

 such specimens, however long kept under suitable conditions, 

 show no sign of winter rot. Perhaps in such instances the 

 mycelium has by some means been checked early in its 

 development. The whole subject requires to be thoroughly 

 investigated before we are in a position to state definitely its 

 cause. 



Infectious chlorosis. Dr. Clinton has noted the occurrence 



