106 CULTURE OF FARM CROPS. 



12. Causes of the Attacks of Must, Mildew, fyc. 

 As already noticed, Professor Henslow is inclined to 

 believe that both rust and mildew proceed from the 

 same fungus (uredo linearis) " under different forms or 

 states of fructification." The Professor states that he has 

 observed the mildew fungus (puccinia graminis) mixed with 

 the rust fungus (uredo rubigo) in a way which strength- 

 ens his opinion j further observations are, however, required 

 to decide the point. A popular notion connected with the 

 blight of wheat by mildew is that " the berberry bush (ber- 

 beris vulgaris) is in some way or other frequently connected 

 with" its production. This opinion is, however, founded 

 apparently upon conjectural notions, or upon carelessly 

 made observations ; and requires to be put to the test of 

 a rigid examination and experiment before it can be re- 

 ceived as correct. Although ergot is generally supposed to 

 be a disease which attacks rye, still, as Professor Henslow 

 remarks, a close investigation of the wheat crop will proba- 

 bly result in proving that it is more frequently to be met 

 with than is supposed ; the Professor suggests that should 

 the ergot even prove abundant in a wheat crop, it will be 

 worth while to pick the diseased grains out from the rest of 

 the sample, not only for the purpose of purifying the remain- 

 der, but for sale ; the ergot being a peculiarly valuble me- 

 dicine in competent hands, although it is, when partaken 

 of in flour, highly dangerous. Professor H. Y. Hind, of 

 Trinity College, Toronto, has made very elaborate investi- 

 gations in the diseases which attack wheat of the class 

 now under description. The result of these he has given 

 in a report to the Canadian Government. The points 

 involved are of such importance that we here re-pro- 

 duce the major portion of the Professor's remarks on 

 the subject: "Ammonia, we know, exists in the atmo- 

 sphere, probably to the extent of one part in ten mil- 

 lion parts on the average. At times the quantity of am- 

 monia present is much greater than the above ratio, at 

 other periods less. Eain water contains on an average 

 nearly one part of ammonia to the million, and of nitric 



