296 Canadian Record of Science. 



(3) essentially the same relations are manifested in Spiraea ; 



(4) shrubs which had not been top-pruned in 1903, exhibited 

 no special phenomena of growth in 1904, apart from the 

 somewhat general luxuriance common to all trees and shrubs. 

 Finally, the reduced leaves of Lonicera are to be regarded as 

 juvenile forms which have been restored under special condi- 

 tions of growth, and such reversion has been accomplished 

 through correlation, in opposition to the influence of light, 

 which, acting by itself, would tend to produce the opposite 

 result as Goebel has shown in the case of Campanula rotundi- 



folia in particular. 1 



In such types as Weigela, Hydrangea, Berberis thunbergii, 

 and B. vulgaris, Euonymus, Ampelopsis quinquefolia, various 

 species of Vitis, Shepherdia canadensis, Syringa vulgaris and 

 many others which will readily occur to one, there is no essen- 

 tial variation in the mature foliage, as between the vegetative 

 and the reproductive shoots, but all conform to one type, 

 within certain narrow limits. In Celastrus articulatus there is 

 a more or less well defined variation of leaves which places 

 some of them distinctly beyond the type form, but such varia- 

 tion is not in any special sense distinctive of either the 

 vegetative or the reproductive shoots, and these instances 

 serve to enforce the idea that the foliage of the reproductive 

 shoot cannot be taken even generally, as affording the real 

 basis for type forms. 



It has been noted that special variations of form and size 

 of leaf often arise upon the same branch or under special con- 

 ditions of growth. Thus in Lonicera tartarica (Fig. 4 : 1-12), 

 it appears that in four sets of leaves, the lowest of each series 

 (1, 4, 7, 10) is always the smallest and deviates most widely 

 from the type, the same rule holding true of the lowest mem- 

 ber of the series as a whole (1). This relation was found to 

 be true of a shrub greatly modified by pruning and conditions 

 of nutrition. But the same rule holds true to a more limited 

 extent in a shrub which only partially expresses the effects of 

 such conditions. (Fig. 5 : 1 and 8). In the case of normally 

 developed branches, however, (Fig. 2 : 1-7) this rule does not 



1. Organography, 242, 243. 



