MacDougal : Somk Cokkri.ations of Leaves 507 



lar reactions are shown by the elder [Savibucits nigra)* He also 

 found that the stipules of Vicia Faba were increased in superficial 

 extension two to six times beyond the normal by the excision of 

 the laminae in an early stage of development, and a similar exag- 

 geration in the stipules of Lathynis Aphaca resulted from the ces- 

 sation of elongation or extension of the shoots. This correlation 

 is not present in all plants, however, and not even in all Papilion- 

 aceae, since it was seen that the excision of the laminae of Phascolus 

 multiJJorus had but little effect upon the size and structure of the 



laminae.f 



The excision of the leaves of Aristolochia, in the course of the 

 present experiments, did not cause any notable increase in size of 

 the stipules as seen by general inspection, although no examina- 

 tion of the internal structure was made. 



Kronfeld made a series of experimental tests of this matter in 

 1886, and found that the stipules of Pyrctlirnui Iudic7tin, Rosa 

 sevipcrjionns, Rubus fruticosus, R. Idaais, Sida Napaca, Trifoliiim 

 filifovme and Urtica urcns were not sensibly increased in size by 

 the destruction of the laminae. The destruction of the laminae of 

 Pyrns Mains was followed by an increase of the superficial expan- 

 sion of the stipules amounting to a hundred per cent. The exci- 

 sion of the laminae of Pisnm sativum was followed by an increase 

 of the size of the stipules amounting to from fifty to one hundred 

 per cent., while the excision of the stipules alone seemed to have 

 the effect of causing earlier flower-formation. % 



Stomata were found on both normal and abnormal stipules in 

 Pnmns in my own experiments. No examination of the number 

 of stomata on the adjoining surfaces of the stem were made, but 

 Braun has found that defoliation causes the formation of an in- 

 creased number of these organs. § The enlargement of the stimu- 

 lated stipules of Prnnns had apparently not been accompanied by 

 a multiplication of the epidermal cells, since these elements were 

 both larger and wider in surface view than the normal. 



*Goebel. Organography of Plants, i : 210. 1900. 



f Goebel. ( Beitrage zur Morphologic und Physiologic dcs Blattes. ) Bot. Zeitung, 

 38 : 836-837. 1880. 



% Kronfeld, M. Ueber die '• Correlation dcs Wachstums." Bot. Zeitung, 44 : 

 846-849. 1886. 



\ Braun, K. Ucber Verandcrungen ira Gewcbe entlaubter Stengel und Zweige. 

 (Inaug. Diss.) Erlangen. 1899. 



