238 



PRINCIPLES OF PLANT-TERATOLOGY. 



with a change in phyllo taxis, as in Labiatse, and in the 

 elm, Buddleia, etc. 



Celakovsky points out that double leaves are the 

 result of the strife waged during the ontogeny between 

 the two tendencies, viz., towards division on the one 

 hand, and towards fusion on the other. 



It is obvious from what has gone before that no 

 general law can belaid down to account for the origin 

 of forked or double leaves. Each case must be decided 

 on its own merits. 



Coming to the consideration of terminal leaves we 

 meet in these with a phenomenon which is in direct con- 

 tradiction to the modern notion that leaves are always 

 lateral appendages on an axis. Instances of normally 

 terminal foliage-leaves and cotyledons have been 

 already cited ; other instances of foliage organs which 

 are normally terminal are afforded by the stamen of 

 Najas and the carpel of the "bulrush" (Typha), and 

 the radially constructed* sterile sporophyll of the cone 

 of Encephalartos. The modern view is that stamens 

 and carpels are but modified foliage-leaves, so that in 

 actuality there are plenty of instances of terminal foliar 

 organs. The majority of present-clay botanists hold 

 the view, moreover, that the terminal position of the 

 foliar organ, whether it be cotyledon, foliage-leaf, or 

 sporophyll, is a secondary phenomenon, and that the 

 lateral position on the axis is the original one, 

 the growing stem-apex having always, from earliest 

 times, topped the whole. This view should be 

 regarded, however, as a fallacious and artificial one, 

 based as it is on mere appearances, and not on sound 

 data of comparative morphology. It is impossible to 

 discuss the whole matter here. Allegiance to the 

 ' 4 phy ton-theory " of Gaudichaud, Schultz-Schultzen- 

 stein, Delpino, and Celakovsky, may merely be 



* Nearly all terminal foliar organs are radially constructed, at any rate 

 in their external configuration. The leaf of Gesnera Geroltiana, cited by 

 Morren, is an exception. On the other hand, radially-constructed leaves 

 are often found in a lateral position, e. g., peltate or pitcher-leaves of elm, 

 lime, Pelargonium, etc. 



