168 Plant Tissue Culture 



material. This, then, has been used as a basis in 

 interpreting results of experiments of this sort. 

 Records. Each worker will have his own prefer- 

 ences as to records, which he will adapt to his own 

 particular problems. This laboratory's records, 

 as regards root cultures, may be worth presenting. 

 All records are kept in 5 X 7£" notebooks contain- 

 ing about 120 pages, cross-ruled at \" intervals. 

 This book is of a size that will slip into a coat 

 pocket (Fig. 41). The rulings permit the organi- 

 zation of the page into both horizontal and vertical 

 columns and are close enough together so that a 

 great deal of information can be placed on a single 

 page. Three sample pages will suffice to indicate 

 the ways in which such pages can be organized. 

 The three sample pages indicate clearly the way 

 in which routine numerical records are kept. In 

 addition, photographs are taken of typical roots 

 in each important experiment chosen to represent 

 as nearly as possible the average length and 

 growth habit of those grown in each solution or 

 environmental complex. Thus, in Example 2, 

 root No. 136 was set aside for photographing since 

 it most nearly approximated the average of the 

 group. The actual figures were: 



Average increment = 24.8 mm. 



No. 136 = 42—18 = 24 mm. 



