714 Notes. 
included lamina was carried into the air. The 1 first-leaf’ thus performed the 
functions of a cotyledon. 
This may be considered to be the converse of the state of affairs met with in the 
geophilous Peperomias. 
On the other hand, although without doubt there is an inversion in fact, this case 
of abnormal germination in Arisarum appears to lend support to the argument put 
forward in connexion with the germination of the Peperomias, since the ‘ first-leaf ’ is 
shown to be physiologically capable of performing cotyledonary functions. Whether 
or not it is legitimate to argue that in an abnormal case of this kind the ‘ first-leaf’ is 
really showing a recapitulation of lost functions, and that it is in fact also morphologically 
the second cotyledon, is an open question. 
The morphological relations of the cotyledon and ‘ first-leaf' in the Araceae were 
pointed out in the paper already referred to , 1 and it does not seem improbable that 
the £ first-leaf ’ and the suctorial cotyledon really stand to one another as a pair of 
cotyledons with different functions. From this point of view the example described 
by MM. Buchet and Gatin, as far as it may be held to be of value in this connexion, 
lends support to the views put forward that the 1 first-leaf’ of Monocotyledons may 
represent the second cotyledon of the monocotyledonous embryo. 
A. W. HILL. 
Kew. 
ON THE OCCURRENCE OF DIFFERENT TYPES OF HAIR IN THE 
WALLFLOWER. — The well-known hairs on the leaves of the wallflower are 
spindle-shaped, with a short stalk at the middle attaching them to the leaf. They 
may be described as two-armed (malpighian) hairs having the two arms in the same 
straight line and parallel to the surface of the leaf . 2 Each hair, including its stalk, 
consists of a single cell, and the surface of the spindle-shaped portion is studded with 
knobs containing carbonate of lime. Fig. 1, a shows the outline of a hair of this 
type as seen from above, i. e. in a surface-view of the leaf. In a lower focus the stalk 
would be represented as a small circle in the middle of the hair. 
No other type of hair appears to have been recorded in the wallflower, or to occur 
on the leaf or stem of the mature plant, except on the lower leaves of some lateral 
branches. On the cotyledons, however, other forms are found, viz. three-armed hairs 
(Fig. 1, b) and hairs with four (Fig. 1, c, d), five (Fig. 1, e) and, rarely, six arms. 
The two-armed type of hair, characteristic of the mature plant, occurs also on the 
cotyledons, but is usually far outnumbered by hairs with three or more arms. 
On the upper side of the cotyledons the hairs may be many or few, but the 
proportional number of malpighian hairs (Fig. 1, a) is nearly always small. 
Three-armed hairs appear to be the commonest, but on some cotyledons hairs with 
four or five arms predominate. On the lower side of the cotyledons the hairs are 
usually few, and often mostly of the two-armed type, but hairs with three or four arms 
also occur. 
1 Hill, A. W. in Ann. Bot. xx, pp. 417-422. 
2 Some of the hairs have their arms bent slightly (or, rarely, sharply) upwards, away from the 
surface of the leaf. 
