224 



MOKPHOLOG Y. 



present the only suggestion which it gives of belonging to the 

 leaf series is the fact that the end is divided into three parts, the 

 number of parts in each successive whorl of members of the 

 flower. If we cut across the body of this pistil and examine it 

 with a low power we see that there are three chambers or cavi- 

 ties, and at the junction of each 

 the walls suggest to us that this 

 body may have been formed by the 

 infolding of the margins of three 

 leaf-like members, the places of 

 contact having then become grown 

 together. We see also that from 

 the incurved 

 margins of each 

 division of the 

 pistil there stand 



out in the cavity oval bodies. 

 These are the ovules. Now the 

 ovules we have learned from our 

 study of the gymnosperms are the 

 sporangia (here the macrosporangia). 

 It is now more evident that this curious body, the pistil, is made up 

 of three leaf-like members which have fused together, each mem- 

 ber being the equivalent of a sporophyll (here the macrosporo- 

 phyll). This must be a fascinating observation, that 

 'plants of such widely different groups and of such 

 different grades of complexity should have members 

 formed on the same plan and belonging to the same 

 series of members, devoted to similar functions, and 

 yet carried out with such great modifications that at 

 first we do not see this common meeting ground 

 Fig 2 94 . which a comparative study brings out so clearly. 

 st a !n r en S of r Trii d 446. Transformations of the flower oftrillium.- 

 anther Sl ioSi n ef If anything more were needed to make it clear that 

 on the margin. the ^ arts of the flower of trillium belong to the leaf 



series we could obtain evidence from the transformations which 



