1 -J 1 MORPHUl,()i:Y AN'n rAUASlTIsM OT UltlZOrtON'I A. 



livpha' ill ail agar culture 24 hours old and Text Fig. ill. -J. :{ 

 represents hvphse from diseased seedlings. In culture on a;^ar 

 medium E the sclerotia reach a larger size than on the cotton 

 seedlings, some of them being as nmch as 150^ in diameter. 



I have not been able to consult in the original Atkinson's des- 

 cription of the sterile fungus attacking cotton in America, but Balls 

 quotes Atkinson's description as follows: — 



" The freshlv developed threads branch freely, but not profusely : 

 they are colourless, composed of elongated cells 9 — 11^ in diameter. 

 and 100 200^^ in length. The branches very near the point of attach- 

 ment are a little curved towards the point of growth of the same. 

 At the point of attachment with the parent hypha, the branch is 

 coiuiierably smaller than either the diameter of the parent liyphic 

 or the main part of the branch, and the septum separating the pro- 

 to})lasm of the greater part of the branch from that of the parent 

 hypha. is situated some distance from the latter, usually 15 — 2i),, from 

 the main thread. This portion of the branch, the contents of 

 which are continuous with the parent thread, is clavate in form." 



Other American authors evidently con.sidei' this disease to be 

 due to Rhizoctonia ; thus Duggar and Stewart (10) include it in their 

 paper under the heading "Rhizoctonia in America," and Stevens 

 and Hall(27) give " rhizoctoniose " as a synonym for '-sore shin." A 

 ( omparison of the above description with that of the fungus which 

 has just been described as attacking jute and cotton shows a sub- 

 stantial agreement in all essential points. .Atkinson's measure- 

 ments seem to be slightly larger, but it has already been mentioned 

 that the size of the hyphse varies with the age of the culture. 



Balls states that Atkinson's description applies equally well 

 to the Egyptian ""sore shin" fungus ; it follows therefore that in 

 America, Egypt and India cotton is attacked by Rhizoctonia. The 

 svmptoms of "sore shin" disease agree exactly with those of the 

 present outbreak, but Balls did not obtain any of the sclerotia which 

 occur so abundantly in our cultures and wliieli arc mentioned by 

 Atkinson. The only reproductive organs which he mentions are 

 termed "resting cells," and are stated to arise by the enlargement 



