57 KAN DA— VERBENA 19,-0 



It is necessary to consider whether or not the differences between 

 these plants might not have been induced through adaptation and 

 response to the local conditions in which each type may happen to 

 be growing. Such an influence of local factors can be recognized 

 at Stony Island in different degrees; thus, for instance, while the 

 color of the flowers of V. hastata varies greatly with individuals, 

 without reference to the conditions of the habitat, the shape and 

 texture of the leaves of this species are plainly responsive to the 

 surroundings, those plants growing in dry places having narrower 

 and stiffer leaves than those inhabiting wet situations. 



I believe I have eliminated this possibility in selecting my 

 materials, and those which I regard as intermediate forms are not 

 cases of modifications due to individual differences or adaptation 

 to local conditions. Thus I have found forms 1 and 2 growing 

 under the same external conditions at one location; forms 4, 5, and 6 

 growing together at another place ; and forms 8 and 9 growing at a 

 third spot. 



Cytological observations 



Material and methods 



The spikes of V. angustijolia (rig. 1), V. stricta (rig. 3), and 

 V. hastata (fig. 7), and the form intermediate between stricta and 

 hastata (fig. 5) were collected during July and August 1918 at 

 Stony Island. The apical part of the spikes, the pistils, and the 

 young fruits in different stages of development were fixed in chrom- 

 acetic acid and corrosive sublimate-acetic acid solutions, the former 

 giving the best results. In the case of the pistils and fruits, it was 

 found advantageous to pick off carefully or partially remove the 

 calyx tubes, as they interfered with the rapid penetration of the 

 fixing fluid. Sections of the apical part of the spikes were cut 

 5, 10, and 15 /x in thickness; pistils and young plants, 5 and 7 .5 /x. 

 Flemming's triple stain and iron alum haematoxylin were used, the 

 former giving quite satisfactory results. 



All of the four forms mentioned were examined in more or less 

 complete series. V. angustijolia is chosen as a type for the purposes 

 of description, but most of the statements are applicable to the 

 others also, and they will be mentioned specifically only where 

 differences between them make a separate discussion necessary. 



