i8o BOTANICAL GAZETTE [February 



tubers is a fair index of the comparative intensity of respiration in the tissues. 

 The data from both plant and animal tissues available at the present seem to 

 justify the general indication that catalase action is invariably correlated with 

 the oxidative processes involved in respiration." — Wm. Crocker. 



Respiration of stored wheat. — Bailey and Gurjar'^ have done an excel- 

 lent piece of work on the respiration of stored wheat. Significant literature is 

 well presented and related to the work in hand, and the methods used in the 

 work are clean cut and exact. The contribution has a very important applica- 

 tion in the shipping and storage of grains. They worked with moisture con- 

 tents ranging from 12 to 18 per cent, such as appear in the practical handling 

 of grains. The following are the more important results. 



Respiration gradually and fairly uniformly rises with moisture content up 

 to 14 . 5 per cent in case of plump spring wheat. With the rise of moisture above 

 this percentage the respiration is markedly accelerated. The soft starchy 

 wheats respire more rapidly than the hard vitreous wheats containing the same 

 percentage of moisture. With more than 14 per cent moisture shriveled wheat 

 respires 2 to 3 times as fast as plump wheat of the same water content, due to a 

 larger percentage of embryo in the shriveled grains; with less than 14 per cent 

 moisture there is little difference. 



Freshly dampened wheat respires more slowly than wheat of the same water 

 content that has been dampened for a long time or that has been naturally 

 dampened. The difference is noticeable at 13 per cent moisture, and rises as 

 the moisture rises. Wheat stored at room temperature respires more rapidly 

 than that of the same moisture content at lower out-door temperatures. Un- 

 soundness of wheat caused by the freezing of unripe plants increases respira- 

 tion. This is attributed to the accumulation of glucose in the frosted grains. 

 Increased temperature inci;eases the respiration up to 55° C. When seeds are 

 stored in closed chambers and the respiration taken by 4-day periods, the rate 

 is highest for the first period and diminishes materially in successive periods 

 as the carbon dioxide content rises. The respiration is also reduced in an 

 oxygen free atmosphere, the ratio to that occurring in a normal atmosphere 

 being about 1:2.5. 



Many will think the author's evidence for their viscosity conception of 

 limited respiration is insufficient. They will also question whether the amount 

 of glucose present limits respiration when low moisture has already run respira- 

 tion to so low an ebb. — Wm. Crocker. 



Relation of host and parasite among fungi. — An excellent service has been 

 rendered by Reed'^ in bringing together the extensive and scattered data 

 regarding the susceptibility of more or less related hosts to physiological strains 



'* Bailey, C. H., and Gurjar, A. M., Respiration of stored wheat. Jour, .\gric. 

 Research 12:685-713. igi8. 



'9 Reed, George M., Physiological specialization of parasitic fungi. Mem. 

 Brooklyn Bot. Gard. 1:348-409. 1918. 



