30 Chapters in Modern Botany CHAP. 



phora, Sarracenia, and Darlingtonia alike, the pitcher is 

 developed from what is originally a compound leaf, con- 

 sisting of from two to five pairs of leaflets. But there is a 

 marked tendency to dorsal fusion of these leaflets from 

 apex to base. Such fused leaflets are seen in the broad 

 basal part of the Nepenthes leaf, and in the flaps and lids 

 of the various pitchers. The pitcher itself is a deep dorsal 

 involution of the midrib just above the termination of the 

 fused upper pair of leaflets, except, indeed, in Cephalotus, 

 where, as Dickson clearly showed, it is an involution of the 

 leaf blade. 



Professor Bower by no means agrees with Macfarlane. 

 He interprets the lid of Nepenthes as composed of a single 

 pair of leaflets fused together; on the other hand, the lid 

 of Sarracenia as merely the flattened terminal portion of 

 the modified leaf. 



Goebel lays stress upon the scantiness of the evidence 

 upon which both these ingenious rival theories of the com- 

 plex origin of the pitcher have been erected, and believes 

 that the structure of all the pitchers is very much the same, 

 that all may be derived from a peltate leaf in which a deep 

 involution of the upper surface has occurred. As to the 

 side wings, in which some see the vestiges of leaflets, he 

 regards them as entirely secondary growths. 



We have cited all these opinions and we might have 

 given others just because in their puzzling divergence 

 they illustrate the difficulty, yet fascination, of morpho- 

 logical studies. It is not important to the student to " get 

 up " this doctrine or that ; indeed the teacher may with 

 advantage postpone or even refrain altogether from express- 

 ing his own judgment ; what really is important is that 

 the student should know how such a question is asked and 

 answered partly by a study of the actual form alike in its 

 obvious and in its microscopic structure ; partly by com- 



