| 508 DR. W. R. MCNAB ON WELWITSCHIA. 
tions of the perianth are formed. In the male flower this basal portion is entirely 
absent, and the two lateral parts of the perianth form two shoulders, spreading out on 
each side of the axis, while the punctum vegetationis appears as an elongated projection 
with a rounded end. The breadth at the base is about ‘008 of an inch, while the total 
length of the young flower from base to apex is only about :009. The two lateral 
projections are rounded, and about half the total length of the young flower (fig. 1). 
In no case in the formation of the young flower can the growth be traced to the 
multiplication of a single apical cell, as in the Cryptogams, but always to a complex of 
cells, as observed in the Phanerogams. A dermatogen layer was observed ; the epidermis 
is therefore not formed by the differentiation of an external layer of the outer 
periblem tissues. The flower next in age has the floral axis more elongated, the outer 
parts of the perianth larger ; and a distinct swelling is visible above the first-formed or 
outer parts. These swellings, one anterior the other posterior, are the two inner parts 
of the perianth. They are much larger than the outer parts, and decussate with them. 
. The punctum vegetationis is still projecting and rounded, as seen in fig. 2. The two 
inner parts of the perianth rapidly develop ; and a line of separation soon becomes visible 
at the upper edge. Above the two inner parts of the perianth the axis is expanded, and 
then, near the rounded apex, it contracts. The expanded portions are superposed to the 
outer lateral parts of the perianth, and are the two primordial staminal cushions (fig. 3). 
In the next stage the two staminal cushions are distinctly seen. They are semilunar, 
and with no indication of division into three in the earliest stages. It is thus evident 
that instead of 6 stamens forming, only two primordial stamens are developed. Above 
the staminal eushions the punctum vegetationis is seen as a projection in the centre of 
the young flower. During these changes the outer parts of the perianth become 
enlarged and elongated, while the inner parts have grown, but not to the same extent 
(fig. 4). The parts of the perianth now grow rapidly, and enclose the centre of the 
flower completely; it is therefore necessary to dissect out the central portion in order 
to observe the further stages. On removing the coverings the two staminal cushions are 
well seen, placed laterally, with the punctum vegetationis in the middle (fig. 5). At this 
stage the cushions are still simple; and a small projection may now be seen forming 
anteriorly and posteriorly superposed to the inner parts of the perianth. In the next 
stage the staminal cushions are each seen to form three elevations, the middle being the 
larger, the side one smaller. The six stamens are thus produced by the branching of two 
primordial stamens, and not by the formation of six primary stamens (fig. 6). The suc- 
ceeding stage shows the carpels arising anteriorly and posteriorly and covering the 
punctum vegetationis. 'The stamens also change, the central (lateral) one remaining 
small, while the side ones grow much more rapidly (fig. 7). Looking at the flower from 
the side, the two anterior stamens are seen to be on a level with the top of the carpel, 
while the two lateral ones are considerably below that level (fig. 8). In the flower next 
in age the punctum vegetationis is entirely obscured, the two carpels having grown 
over it, while the six stamens appear as if they were six separate ones (fig. 9). After this 
the carpels grow very rapidly in length, and form the peculiar style-like process, while 
the punctum vegetationis remains very small, as seen in a longitudinal section of the 
p 
