FURTHER DEVELOPMENT OF WELWITSCHIA MIRABILIS, 57] 
On the FurtHER DEVELOPMENT 0f WELWITSCHIA MIRABILIS. 
By F. O. Bowsr, M.A., Camb., Assistant to the Professor 
of Botany in University College, London. With Plates 
XXXII and XXXTIT. 
Since the publication of my paper ‘‘ On the Germination and 
Histology of the Seedling of Welwitschia mirabilis” (‘ Quart. 
Journ. Micr. Sci.,’ Jan. 1881), I have been put in a position to 
study the structure of older plants, some specimens of these 
having been supplied to me from the Kew collections, others 
being kindly presented by Chev. D. J. de Nauet Monteiro. It 
is the object of the present paper to describe the structure of 
these older plants, and to show how it corresponds with that of 
the young seedling as already described. 
Before proceeding to this I must put on record information 
received from Chev. Monteiro by letter. In plants of Welwits- 
chia, which he has cultivated for three to four years, he tells me 
that in one case “the first pair of leaves (or cotyledons) have 
dropped off, one plant has one still on, and the remainder have 
them still.” Further, he states that while they remain the 
cotyledons do not change or grow; that as the stem enlarges 
they become ‘jagged at the base, and on dropping they leave a 
tumid scar, observable in the dried specimens as a circle under 
the true leaves. In the older specimens it is so torn up that you 
might take it for part of the cortical integument, unless you were 
aware of the circumstances.”” These observations of Chev. Mon- 
teiro supply us with the direct proof that the cotyledons wither, 
and since there has never been observed a further development 
of leaves of the main axis after the first plumular pair, we may 
conclude that the latter are the leaves which remain persistent 
throughout the life of the Welwitschia plant (cf. ‘ Quart. 
Journ. Micr. Sci.,’ Jan. 1881, p. 29.) ; 
Root and Hypocotyledonary Stem.—Hzxternal Characters. 
The primary root of the seedling has already been described as 
attaining a length of four to five inches without branching (es: 
p- 19). In a letter Chev. Monteiro describes older plants as 
developing a tap root ‘about eighteen or twenty inches in 
length ;” after attaining this length the root branches repeatedly. 
This was the case in the plants four months old which he sup- 
plied to me. In external appearance the young roots present no 
peculiarity. The roots of plants of medium age are, however, 
