1910.] PUBLIC DOCUMENT — No. 31. 101 



it was difficult to conceive of any plant living under such con- 

 ditions. After the soil had been drenched and the injurious 

 substances washed out, not a single death occurred among the 

 plants. 



The question was put to a number of florists, through a leading 

 florists' journal, why they changed their soil in growing roses, 

 carnations and other plants. None of the gTowers gave a satis- 

 factory reply ; they simply knew from experience that it was not 

 practicable to attempt to grow these crops in the same soil two 

 consecutive seasons. An analysis of the percolated water showed 

 such large amounts of soluble compounds that it is not surpris- 

 ing that the plants failed to grow. 



One occasionally finds instances of what aj)pear to be typical 

 cases of malnutrition in the suckers on stumps of trees on cut-off 

 woodland. Different species of trees develop different symptoms 

 in their leaves when growing from the stumps. In some cases 

 the leaves are abnormally large, and in others they are highly 

 colored and more or less contorted or malformed. Here we have 

 an instance of a small amount of foliage being supplied with food 

 from a root system which formerly supported a large tree, and 

 this excess of food supply causes, as it were, congestion. Chem- 

 ical analyses of these abnormal leaves, made by Mr. G. H. Chap- 

 man in our laboratory, show them to be unusually rich in ni- 

 trates. A feature often observed by us in connection with these 

 growths, but w^hich may possibly be of no significance whatso- 

 ever, is their greater susceptibility to attacks of aphids. It is 

 not improbable, however, that their abnormal chemical condition 

 would affect their natural immunity to attacks from aphids 

 and other insects. 



From the nature of the conditions causing malnutrition, a 

 remedy is not difficult to find. It is first essential, of course, 

 to be careful in the use of manures and fertilizers. If the soil 

 in a house has become unfit for use from the injudicious applica- 

 tion of manures and fertilizers, subsoiling may be done to good 

 advantage. Washing out the soil thoroughly, as previously 

 described in our experiments with roses, woidd also prove helpful 

 in some cases, but it should be pointed out that there is more 

 danger in a soggy soil to cucumber roots than those of roses. If 

 leaching out has to be done when the plants are in the soil, it 



