12 MONOCOTYLEDONEÆ. 
known to have when fully developped, one leaf only with occa- 
sionally a smaller opposite one. In 1861, M* Crocker explained (in 
the Journ. Linn. Soc., 5, p. 65) that, in the case of Streptocarpus 
polyantha, these 2 very unequal leaves were the permanent cotyle- 
dons, and that the plant was really leafless unless one or two small 
upper leaves or the bracts were esteemed leaves. Crocker, in raising 
seedlings of this species, had observed that the cotyledons were in 
germination equal: but that, shortly afterwards, one of them com- 
menced growing much more quickly, and became the apparently 
solitary leaf of the plant. The same curious fact has been lately veri- 
fied by Heilscher (in Cohn Beiträge, 3, pars 1, pp. 1-24). The great 
similarity in habit of other 4-leaved species of Streptocarpus raises 
a presumption that in them their 4 leaf is a permanent cotyledon. 
The peculiar manner in which the single leaf of Chirita monophylla 
continues developping after the plant has flowered raises a strong 
suspicion that this leaf may be a permanent cotyledon. There are 
indeed 1-leaved species, seattered in various genera of Cyrtandreæ, 
of similar habit; such are Didymocarpus pygmæa, Platystemma 
violoides, Trachystigma Mannii, Acanthonema strigosum, Epithema 
Horsfieldii, and all the (6) species of Monophyllea. It is observable 
that only 1 species of Didymocarpus out of 72, and only 2 or 3 of 
Chirita out of 25, exhibit this habit. If it should appear that the soli- 
tary leaves of these are really permanent cotyledons, it will be an 
additional proof of the very elose connection between different genera 
of this Tribe, and may cause us to doubt whether any radical 
improvements remain to be effected in their arrangement. Where 
the species are so nearly allied physiologically i. e. by descent, we 
cannot expect to discover technical characters which will divide them 
out into sharply defined groups. 
