1909.] NATURAL SCIENCES OF PHILADELPHIA. 57 



ACTION OF CHEMICAL SOLUTIONS ON BUD DEVELOPMENT: AN EXPERI- 

 MENTAL STUDY OF ACCLIMATIZATION. 



BY JOHN W. HARSHBERGER, PH.D. 



The phenomena of vegetation lend themselves to experimental 

 study. This experimentation is necessary, because the laws which 

 control the periodicity of plants can be determined only by altering 

 the conditions under which such plants grow. Interest in the periodic 

 growth of plants is perhaps keenest in the Spring, when everyone is 

 observing, in a more or less detailed manner, the gradual awakenment 

 of vegetation. The opening of shrub and tree buds has, as a result of 

 this human interest, long engaged the attention of botanists. The 

 phenomena of bud opening, and the laws to be deduced therefrom, 

 have not been studied experimentally. Every student has been struck 

 by the orderly sequence of the process in any particular district or climate. 

 Each species seems to fill its allotted place in the line of bud develop- 

 ment. The question arises, is this sequence due to heredity, to the 

 character of the reserve food, or the disposition of this reserve food 

 in the buds and twigs of the plant, or is it due solely to the climatic 

 conditions, such as temperature and humidity? The experiments 

 which follow will furnish data which it is hoped will contribute to the 

 answer of the above questions. The only other experiments of a 

 similar nature that have come to the writer's knowledge are those of 

 DeCandolle, mentioned by Schimper 1 as follows: "Zweige von Holz- 

 gewachsen zeigen das gleiche Verhalten wie Samen. A. de Candolle 

 trieb Zweige von Populus alba, Carpinus betulus, Catalpa bignonise- 

 folia [bignonioides ?] und Liriodendron tulipifera die sich theils in 

 MontpelliertheilsinGenf entwickelt hatten vom 4 Februar an in einen 

 Raume dessen Temperatur wahrend der Dauer des Versuches zwischen 

 + 7° und +10° schwankte. Die Genfer Zweige entwickelten ihre 

 Laub-knospen fruher als die aus Montpellier stammenden." 



Experiments of the First Year. 



Eight species were studied the first year in which the experiments 

 were conducted. Twigs from Liriodendron tulipifera, Quercus palustris, 



1 Schimper, A. F. W., Pflanzengeogrophie auf phi/siologischer Grundlage, p. 56. 



