146 PLANT PROPAGATION 



l)clow, tlie tests were purposely made within three weeks 

 of the tree felling', because it was believed green wood 

 rather than seasoned represents more nearly conditions in 

 growing trees. 



Test of Transverse Breaking Strength 



At union * Above union 



point, lbs. point, lbs. 



Plum, first block 2,540 4,750 



Plum, second block 3,160 4,950 



To eliminate possible discrepancy due to the breaking 

 point of the union being closer to the ground, and hence 

 possibly in softer wood, the next block was broken above 

 and below as well as at the union. 



Test of Transverse Breaking Strength 



Apricot, first block . . 

 Apricot, second block 



Tensile strength of one-half-inch strips of apricot : No. 

 1 liroke at union with 1,330 pounds pull; above, 1,550; 

 No. 2 broke slightly below union with 2,870 pounds pull, 

 sl-;jhtly above 1,770, but would not break at union. 



Test of Transverse Breaking Strength 



At union Above union 

 point, lbs. point, lbs. 

 Apricot, seasoned four monfhs 1,930 4,355 



The results, Professor Booth points out, "are very posi- 

 tive and it does not seem at all likely that further tests 

 will invalidate the statement that for many trees the point 

 of union is a real and evident weakness. It is true, how- 

 ever, that all three trees tested were apparently strong, 

 had made vigorous growth and had never broken in anv 

 way. They were about eight inches thick and about 10 

 years old. For orchard purposes this weakness does not 

 appear to be of importance. There is also no' question 

 but that the thickening of the trunk, which usually shows 

 at the point of union, may lessen materially the weakness 

 of the trunk at this point." 



202. Phloem, that portion of a fibro-vascular bundle in 

 plants containing the bast and sieve tissue. In exogens 



