APPARATUS AND MATERIALS 45 



(2) Normal (or Standard] Apparatus, made by competent 

 workmen expressly for its particular work, applicable thereto 

 with convenience and celerity, yielding quantitative results of 

 negligible error, and purchasable at any time from the stock 

 of a supply company. This is the kind best for individual work 

 in a course in Plant Physiology, and for some of the purposes 

 of an elementary course. 



(3) Adapted Apparatus, made up from approximately suit- 

 able articles or appliances, especially those sold for Physics and 

 Chemistry, these being altered to fit their special work, either 

 in the laboratory or by aid of local carpenters, etc. When care- 

 fully made they may be preserved and used year after year. 

 Yielding results qualitatively correct, though quantitatively 

 crude, they are useful for demonstration, and hence serve well 

 for an elementary course in the science, as well as for some pur- 

 poses in the higher course. They are also justified by their 

 lower cost where one cannot afford a better sort, or where the 

 latter is not yet obtainable. 



(4) Make-shift Apparatus, brought together from various 

 common articles temporarily pressed into the service, yielding 

 results not at all quantitative and only crudely qualitative, and 

 justifiable only in lower grade, or nature study, courses, where 

 the doing of things has more meaning than the results. 



It is my belief, representing a conversion from a different 

 view held earlier, that in a college course in Plant Physiology 

 emphasis should be laid upon the acquisition and use of normal 

 apparatus, though by no means to the exclusion of either pre- 

 cision or adapted types. It is rather the spirit than the letter 

 of the normal apparatus that should be kept prominent, and for 

 reasons which I have already explained earlier in this book 

 (page u). I would simply repeat here, in this different con- 

 nection, that the superior merit of the normal apparatus consists 

 in three things: (a) in its ever-read iness for use, conserving time 

 and energy for concentration upon the phenomena to be studied; 

 (6) in the feeling of security and definiteness in progress accom- 

 panying the respect and confidence inspired by its accurate 



