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j50r.LV/C4L GAZETTE 



[APRIL 



and variation of this organism, which causes potato scab, and 

 concerning which we cannot decide as yet whether it belongs to 

 the Eumycetes or to the bacteria. 



Morbid histology of the various diseases presents a large field 

 for activity. Concerning many diseases our knowledge in this 

 regard is as yet really nil. It may be in many cases that such 

 knowledge will not affect practice, but in many cases it surely 

 has done so. Its utility appears clearly in relation to cereal smuts, 

 tree surgery, etc. 



The whole question of disease-resistance and susceptibility is 



and 



the 



mechanical 



the factors of air, soil, or heredity causing variation in resistance, 

 and the possibility of artificially changing these factors. Breeding 

 for disease-resistance is a special problem of extreme importance, 

 involving knowledge of the factors of resistance and susceptibility, 

 the needs of cultural conditions, and laws of breeding. Notable 

 progress has been made with many crop plants, as oats, cabbage, 

 asparagus, cantaloupes, carnations, flax, melons, and cowpeas. 



Hibernation of the parasite has been the subject of much study. 



some cases it offers the key to prophylaxis. It is, of course, 



In 



inseparably linked in many 

 seems also sadly in need of 

 training. Indeed, an ecolog 



sound 



e> 



environments 



expenmen 



should be very productive. Problems abound on the border 











