FACTORS IXFLUEXCING RKPRODUCTION 



843 



pidity of manipulation and is made with a specially devised apparatus 

 which is inexpensive and can readily be carried into the field.^'* 



By the Truog method the decomposed humus was found to be neu- 

 tral, the raw humus strongly acid, and the mineral soil of medium 

 acidity. 



Tests at the end of the season to determine the extent to which ex- 



I I I I I I I 



I" ?" :S~ ^ .=" 



Date of MecLsurement 



the growth of balsam fir (Abies balsamea). See figure i 

 for acidities 



posure had diminished acidity showed that during the period of the 

 experiment the diminution was negligible. 



Results I 



Coniferous Transplants. — The measurements showed that the growth 



of both fir and spruce was most rapid on the mild humus, effectually 



"Apparatus can be secured from the Central Scientific Co., Chicago, for $5. 



