AN ABNORMAL LEAF IN FBUNUS LAUROCERASUS. 323 
Zaurocerastts, one of the leaves of which presented, in a marked manner, 
the phenomenon of fissiparous division. The petiole of the abnormal 
leaf did not exhibit any noteworthy peculiarity, and the ordinary scars 
left by the deciduous stipules on either side of its base were visible. 
The petiole, however, supported two laminae, placed back to back, and 
united by their midribs* to within about an inch from their extremities, 
which were perfectly free from each other. These laminae stood ver- 
tically, their edges being directed towards and away from the axis ; 
and, as they were placed back to back, the shining surfaces, correspond- 
ing in structure to the normal upper-leaf surface, were directed laterally 
outwards. In the axil of this abnormal leaf were two axillary buds, 
placed side by side. 
From the existence of two distinct leaf-apices, and of two axillary 
buds, it is evident that the condition here is not due to an accidental 
exuberance in the development of the leaf, but is produced by a true 
fissiparous division, which, had it been complete, would have resulted 
in the replacement of a single leaf by two leaves. It is worthy of re- 
mark that in the most common form of fissiparous division of a leaf, 
the two resulting portions stand in the plane of the primary lamina, 
as is seen in monstrosities where the extremity of a leaf is more or less 
deeply bifid, a branch of the forked midrib entering each of the re- 
sulting lobes. In the monstrosity under consideration, however, the 
two laminae are placed at right angles to what would have been the 
plane of the primary lamina. The diagrams on Plate LXX II. will help 
to render this intelligible. 
Whether or not there mav be an analogy between this monstrosity 
in PfKMM Lanrocerasus and the four-winged filaments in certain 
double flowers described by Dr. Masters (Report of Proceed, of In- 
terna*. Bot. Congr., London, 1866), I am scarcely prepared to say; 
I can judge, the condition described by Dr. Masters ap- 
pears to be rather an exuberance of growth than a distinct fission. 
It is possible, however, that we have a normal counterpart to the above- 
described monstrosity in cases where a staminal filament is forked in 
snch a manner that the anthers borne by the branches are placed back 
to back, i. e. facing laterally outwards, as in Adoxa, Befck, Owyiaw, 
* It would, of course, be more correct to say "not separated at their mid- 
ribs ;'• but it is evident that the incorrect expression is better adapted for de- 
scriptiYe purposes. 
