July, 1907.1 KUMAKIRL—BEL. OF PLANT GROWTH TO ROOT SPACE. 131 



4 „ (NH 4 ) 2 S0 4 



6 „ K 2 S0 4 . 



The small pots held 2 kilo soil while larger pots 10 kilo. 



The manure was certainly abundant as the number of plants 

 grown per pot were only two. The objection that there was 

 not enough of mineral nutrient in the small pots would there- 

 fore have been impossible. 



On October 10, 15 seeds of spinach and 15 seeds of barley 

 respectively were sown in each of the large pots, while the 

 small pots received 8 of spinach seeds and 8 of barley grains 

 respectively. 



The young plants were thinned October 28 to two plants 

 of equal size in all the pots. 



The spinach plants showed at an early date a considerable 

 difference in height. 



The measurements were, cm. : 



Small pots | 



December 22. January 17. February 2. 



7.5 8.7 9.7 



8.1 10.0 10.6 



Average 7.8 9.3 10.1 



12.1 13.9 16.9 



12.4 14.2 17.8 



Large spot j 



Average 12.2 14.0 17.3 



These plants were harvested on February 2 with the fol- 

 lowing result, g: 



Small pots. Large pots. 



Total harvest < 



I 23.0 49.3 



Average ...... 20.2 49.15 



An examination of the roots in both cases revealed an im- 

 mense difference, as in the small pots a very great number of 

 roots were growing along the walls, very much more so than 

 in the large pots. 



The barley plants also showed a very marked difference in 

 height, as will be seen from the following data in cm. : 



