PLANT PHYSIOLOGY. 49, 



more work remains to be done before a decision can be reached 

 as the economic value of electrical discharge. The effect of the 

 discharge on crops other than clover-hay and spring-sown cereals 

 is not definitely known, and no experience has been gained 

 of the actual working of field installation in practical farming. 

 Further, the period in the life of the plant when the current 

 may be most economically applied, and the strength of current 

 which should be used at different stages of its growth, are not 

 yet known with precision. As regards the field experiments, 

 the most recent development has been in the direction of testing 

 the effect of higher wires. Hitherto the wires have been 7 feet 

 high, and supported by numerous poles, which in practice would 

 interfere with farming operations. In the new experiments 

 the wires will be 18 feet high and there will be fewer poles. The 

 difficulty in the case of field experiments is that one particular 

 set of conditions must be kept constant throughout several 

 seasons before a result can be relied upon, and every change in 

 the conditions must be tested for the same length of time. Thus 

 a set of experiments lasting through several seasons is required 

 for each strength of current, each crop, and every change in 

 the daily period during which the current is applied. On the 

 other hand, there is no doubt that electrical discharge will 

 increase plant growth, and it is hoped that it will be found 

 possible to continue the patient experimental work that has 

 been going on for some years, for it seems certain that sooner 

 or later electricity must play an important part on the farm 

 in increasing crop production. 



In the foregoing account, we have been unable to do more 

 than refer to the main lines of research in progress at the Imperial 

 College of Science. A number of subsidiary investigations are 

 being conducted, but these, although important enough in their 

 bearing on other research, are too remote from farming operations 

 to be detailed here. One branch of work may, however, be 

 referred to briefly, although it is not aided from the funds of 

 the Ministry of Agriculture and Fisheries. The Food Investiga- 

 tion Board of the Department of Scientific and Industrial 

 Research have provided the means for a study of the physiological 

 aspect of cold storage. Estimations are being made of the 

 changes that go on in the fruit throughout the whole period of 

 storage of different varieties of apples and pears stored under 

 ordinary conditions and at low temperatures. These estimations 

 are being made in an attempt to discover the cause of the 

 " mealiness " which develops in apples and pears stored too 

 long. Storing at low temperature delays the onset of the 



