FRUIT-BUD FORMATION 57 



nence has been the appUcation of the various "essential" 

 elements of plant nutrients, either by means of cultivation, 

 green-manuring, or animal or artificial manures. These 

 various treatments have not ])een without their results from 

 an economic standpoint, but the field still remains open to 

 investigators interested in determining the part played by 

 these elements and their inter-relation. 



The investigations and interpretations of Kraus and Kray- 

 bill are highly significant and are of interest in this comiection. 

 The statements or premises which they have postulated 

 are given here verbatmi. The abbreviations follow- 

 ing the various items are: M = moisture; N= nitrogen- 

 complexes (especially nitrates) ; C = carbohydrates. These 

 formulae are not a part of the original article and they are 

 not to be taken as actual ratio expressions, 



I. Though there be present an abundance of moisture 

 and mineral nutrients, including nitrates, yet without an 

 available carbohydrate supply, vegetation is weakened and 

 the plants are non-fruitful; M/N — C= non-fruitful. 



II. An abundance of moisture and mineral nutrients, 

 especially nitrates coupled with an available carbohydrate 

 supply, makes for increased vegetation, barrenness, and 

 sterility; M/N+C= non-fruitful. 



III. A relative decrease of nitrates in proportion to the 

 carbohydrates makes for an accumulation of the latter, and 

 also for fruitfulness, fertility, and lessened vegetation; N/C 

 — N = fruitful. 



IV. A further reduction of nitrates without inhibiting 

 a possible increase of carbohydrates, makes for a suppres- 

 sion both of vegetation and fruitfulness. C — N = non-fruitful , 



According to these views, the behavior or response of the 

 trees as regards growth and fruitfulness is not entirely a 

 matter of total amount of nutrient or food materials avail- 

 able, but a proper balance or relation between them as well. 



