BY PROF. BAYLEY BALFOUR AND W. W. SMITH. 
281 
is persistently meristematie throughout, and in the mid- 
line of its upper surface at least, for it is there that the 
flower-buds arise in linear series but not in age sequence 
from below upwards or from above downwards. Young 
and old are intermingled throughout the length.* 
It may be asked what are the grounds upon which we 
base the views expressed above. We will explain. 
To do this we recall the well-known features of germina¬ 
tion exhibited by other genera of Gesneracese. Let us 
begin with Streptocarpus .t Taking in the first instance 
S. polyanthus , Hook., we find within its seed at the period 
when it is ripe the protocorm of the embryo as an elongated 
ovoid body showing towards the apical end two lateral 
outgrowths of equal size—-the cotyledons. There is no 
trace of a primordium of a primary root, nor of a plumular 
bud, and there never is. When germination takes place, 
the whole surface of the protocorm becomes covered with 
absorptive hairs. One of the cotyledons is arrested in 
growth, the other elongates and growing rapidly by basal 
intercalary growth forms in time a broad green lamina 
without stalk. Soon a series of adventitious roots develop 
from the hypocotyl and also from the cotyledon base. 
The top of the hypocotyl where the cotyledons are does 
not in this species show much growth in length, and the 
cotyledons remain about the same level. Soon the smaller 
* A cotyledon is often like a leaf in its later stages of life, and is perhaps 
most commonly spoken of as a leaf. But a leaf is an organ of the epicotylar 
axis proceeding from the plumular bud. The leaf arises as a lateral structure 
from one of its nodes. A cotyledon as an extension of the embryonic proto¬ 
corm may proceed from the end of the protocorm or from its sides, and does 
not present in its evolution the fundamental criteria required by the founda¬ 
tions of morphology for being reckoned the homologue of an epicotylar leaf. 
Entering this caveat, we are content in our systematic description to speak 
of the vegetative body of Moultonia as a leaf with a petiole and having 
epiphyllous inflorescence. 
t Crocker, “Notes on Germination of Certain Species of Cyrtandrese ” 
in journ. Linn. Soc. v. (1861), 65, t. iv.; Dickie, “ Note of Observations 
and Experiments in Germination” in Journ. Linn. Soc. ix. (1867), 126; 
Dickson, “ On the Germination of Streptocarpus caulescens ” in Trans. Bot. 
Soc. Edin. xiv. (1888), 362, pi. xiv. ; Hielscher, “ Anatomie und Biologie 
der Gattung Streptocarpus” in Cohn’s Beitrage iii. (1888), 1, tt. i.-iii.; 
Fritsch, “ Ueber die Entwicklung des Gesneraceen ” in Ber. d. deutsch. 
Bot. Gesellseh. (Gen. Versamml.) xii. (1894), 26. 
Crocker was foreman of the Propagation Department, Royal Gardens, 
Kew, and was the first to record the features of germination of Streptocarpus. 
His observations were exact, and he distinctly states that there is an absence 
of all trace of plumule. His figures found their way into the botanical text¬ 
books of the period. We mention this because his work, as well as that of 
Dickie and Dickson, is ignored by Hielscher, who is quoted in most modern 
German books as if he were the observer who first made known the facts. 
