287 
of the Mistletoe ( Viscum album , L). 
In the female flowers the perianth 1 consists usually of two 
dimerous alternating whorls of scale-leaves, which cohere, more 
or less, at the base. Their position will be readily understood 
by a glance at Fig. 1, which has been copied from Eichler 2 . 
The two carpels which compose the ovary continue the regular 
alternation. No exception has come under my observation 
with regard to the number of parts composing the lateral 
flowers, whereas in the terminal flowers of shoots bearing three 
foliage-leaves only one whorl of perianth- leaves, alternating 
with the three scale-leaves which precede the flowers, was 
observed (Fig. 4). Wydler mentions a case in which a female 
terminal flower, preceded by two scale-leaves, had also a 
trimerous perianth. An increase in the number of perianth- 
leaves beyond four has also been described by the same 
author, and is very likely to be explained in the same way as 
a similar increase of the organs composing the male flowers, 
which will be treated of later. Whether any variation in the 
number of carpels takes place I am unable to say. 
The male flowers are, on the whole, built on the same plan 
as the female ones, but every trace of an ovary is absent in 
their centre. Each perianth-leaf bears six to twenty pollen-sacs. 
Hofmeister 3 and van Tieghem 4 consider each of these structures 
(taken as a whole) as a single leaf. The former bases his view on 
the development, which shows that it arises apparently as one 
organ ; while the latter bases his view chiefly on anatomical 
grounds, but he is careful to call them simply polliniferous 
sepals (‘ sepales polliniferes’) ; he does not call them stamens, 
as one would expect. Eichler, on the other hand, who 
based his view on a comparison between the structure of the 
flower of the mistletoe and that of nearly allied forms, came 
to the conclusion that each consists of two parts, namely of 
1 I have never seen the so-called ‘ calyculus ’ of the flowers. It is frequently- 
mentioned that it does not occur regularly, and it seems to be certain that it is 
only an outgrowth of the axis without leafy character. Compare Hofmeister in 
Flora, 1854, P- 644 (note); Wydler, in Flora, i860, p. 445; Eichler, Bliithendia- 
gramme, p. 553. 
2 1. c., Fig. 236, b. 
4 Ann. d. Sc. Nat. serie 5, Tome xii. p. 101. 
1. c., p. 539. 
