430 BOTANICAL GAZETTE [JUNE 
greater surface of leaf than is borne on the normal year’s growth 
of stem. 
As clearly noted by Kraus, and emphasized almost humor- 
ously by Meissner, the length of the needles formed during dif- 
ferent years on uninjured trees varies considerably with the 
prevailing climatic conditions. This appears undisturbed only 
in table VIII, which is introduced rather to show what might 
have been expected during these years, of the smaller trees, if 
their development had not been interrupted. There is abso- 
lutely no reason for suspecting an automatic periodicity in the 
length of the needles. These constant yearly fluctuations can 
only be regarded as less conspicuous symptoms of the same gen- 
eral state of matters which when exaggerated finds expression 
in the various phases of dwarfing of transplanted trees. In the 
latter case, that of transplanted trees, if we seek’ to apply the 
old “law of the minimums” it is probably safe to say (overlook- 
ing the possibility that this is in part an instance of “ correla- 
tion") that the inability to get a proper supply of water is the 
factor which places the limit on growth. This must often be 
true, too, when the variations depend on the “Klima;” and the 
summer of 1897 (see table VIII) was indeed a destructively dry 
one in Bloomington. But the early part of the same season was 
unusually cold, and what part of the failure of the needles to 
reach their average length was due to the drought, and what to 
the late spring, cannot be said. To analyze the complex of con- 
ditions comprehended under a season’s ‘‘weather”’ is not imme- 
diately practicable. 
Even in the relatively simple case of transplanted trees 
Reinke probably went astray when he attempted any further 
analysis of the cause of dwarfing. He satisfied himself, in some 
way, that enough water was absorbed through the periderm of 
the old roots to cover the loss by transpiration, and concluded 
therefore that the normal development of the leaves is in part 
dependent upon the root pressure. Very probably it does 
depend upon the amount of water present within the plant; but 
before one ascribes a share in it to actual root pressure, it should 
