106 



Mycologia 



sote, the middle ones are by far the most toxic. Common salt is 

 an excellent preservative for inside timbers, where leaching is 

 impossible. 



Experiments in the use of asphaltum and other substances as 

 dressings for wounds of trees," by John Boddy. Lead paint has 

 been tried thoroughly and found unsatisfactory unless applied 

 at least once a year. Coal tar, the substance most used at 

 present, has a caustic effect on the cambium and is also less 

 durable than supposed. Asphaltum, or pure bitumen, derived 

 from petroleum, is the very best dressing for trees of all kinds. 

 It is applied hot from a kettle, as in the case of street-paving. 



" The importance of sanitation in the control of certain plant 

 diseases," by L. R. Jones. It is possible that we depend too 

 much on spraying, to the neglect of sanitation. Diseases of 

 cabbage were used in illustration. If the "yellows" (Pusarium) 

 appears in a field, it rots all the heads and there is no chance of 

 growing cabbage in that field even six years afterwards. The 

 only hope is in one variety which appears resistant. Another 

 field may show only ''wilt" (Phoma), and still another only the 

 common " black rot." Each disease is introduced locally and 

 remains. Fields must be kept free of these diseases, and change 

 of crops must be resorted to if necessary. 



" The effect of Gymno sporangium upon the transpiration and 

 photosynthesis of apple leaves," by H. S. Reed and J. S. Cooley. 

 The authors reported quantitative experiments upon the tran- 

 spiration and photosynthesis of healthy and diseased leaves- 

 Transpiration records were taken in the field and photosynthesis 

 records were taken in the laboratory by use of Ganong's photo- 

 synthometer. Both agreed in showing diminished activity on 

 diseased leaves. 



" The toxicity of plant acids and enzymes," by M. T. Cook and 

 J. J. Taubenhaus. Laboratory experiments with picked fruits 

 are not conclusive, owing to the fact that the enzymes which 

 guard against fungi in the field may die after picking. For 

 example, pears may contain living enzymes 45 days after picking, 

 while in apples the death of the protecting enzymes may occur 

 much sooner. 



