Tricotyly and the Arrangement of Leaves. 377 
the cotyledons and especially a splitting equally deep on 
the two sides may involve an alteration in the disposition 
of the leaves. This, of course, is by no means a neces- 
sary consequence, but the present case indicates that the 
internal cause is not necessarily limited in its operation 
to the cotyledons. 
Terminal leaves have hitherto been regarded by tera- 
tologists as very rare occurrences, but my tricotylous 
races of Antirrhinum majns have afforded me the oppor- 
tunity of observing them repeatedly and in hundreds of 
specimens (Fig. 81). 
A well-known instance is the great terminal leaf of 
Gesncra Geroltiana described by MORREN and reproduced 
by MASTERS/ This specimen bears only one normal 
pair of leaves, and above these an erect leaf of double 
the normal size. In the figure we can see the node at which 
this is inserted; and the simplest explanation of this 
remarkable phenomenon is that, for some reason or other, 
the growth of the second leaf of the pair, as well as that 
of the terminal bud was impeded in early youth. BER- 
NOULLI mentions a similar apparently terminal leaf of 
Coffea arabica, and was able in this case to confirm the 
correctness of this supposition by microscopical obser- 
vation. 2 He also describes a shoot of Fuchsia macro- 
stem ma which bore a funnel-shaped leaf at the top. 
The races of the Snap-dragon, which we have already 
mentioned bear every variety of these structures. These 
may consist of single or of double leaves, or of leaves 
grown together in the shape of a funnel. All inter- 
mediate stages between these and the normal plants oc- 
J CH. MORREN, Bull Acad. Brig., Vol. XVII, Part II, p. 387; 
M. T. MASTERS, Vegetable Teratology, p. 88, Fig. 40. 
2 G. BERNOULLI, Ueber schcinbar terminate Blatter, Botan. Zei- 
tung, 1869, P- 19- 
