KNUDSON: CAMBIUM DEVELOPMENT IN AMERICAN LARCH 273 



while in Taxodium distichum the same conditions prevail as in 

 the broad leaves. 



Buckhout* made during a period of four years caliper measure- 

 ments of European larch at intervals of five days during the 

 growing season. The measurements were made at breast height 

 and the age of trees experimented upon is given as 45 years. He 

 found that the formation of leaves was coincident with the begin- 

 ning of diameter increase. The beginning of this increase was 

 close to April 25, during the four years. He found a gradual 

 increase from this date until about July I, when further growth 

 in diameter practically ceased. The data secured from this 

 method of measurement are not, as he himself realized, entirely 

 conclusive, on account of the errors which may result from the 

 swelling and shrinking of wood and bark with the varying moisture 

 content. 



From the horticultural side gross investigations have been 

 made by Keffer,f Goff,| Cranefield, and others on the duration of 

 growth in fruit trees. Their work is concerned with the develop- 

 ment of shoots and on the duration of wood increase as determined 

 by the readiness with which the bark could be peeled. The work 

 of these men will be considered in a subsequent paper. 



METHODS OF INVESTIGATION 



For the investigation during 1909, four larch trees of approxi- 

 mately thirteen years of age were used. These trees are hereafter 

 designated for convenience as trees A, B, C, and D. The trees 

 originally grew in a swamp in Oswego County, New York, but 

 were transplanted in 1902 to the nursery on the Cornell University 

 Campus, on land which slopes gently to the west and is of a well- 

 drained, heavy clay soil type. The trees were planted four feet 

 apart and were shaded on the east and west sides but not on the 



* Buckhout, W. A. The formation of the annual ring of wood in European larch 

 and the pine. Forestry Quarterly 5: 259-267. 1907. 



t Keffer, C. A. The early growth and training of apple trees. Tenn. Agr. Exp. 

 Sta. Bull. 14: 1-16. 1901. 



t Goff, E. S. The resumption of root growth in spring. Wisconsin Agr. Exp. 

 Sta. Ann. Rep. 15: 220-228. 1898. 



Cranefield, F. Duration of growth period in trees. Wisconsin Agr. Exp. Sta. 

 Ann. Rep. 17: 300-308. 1900. 



