i 7 4 
Notes . 
confined to special structures brought into existence entirely by the 
stimulation of the parasite. Their history may be compared, in its 
general features, to that of the ‘ bladder-plums ’ produced by the 
attacks of Exoascus. 
ALFRED W. BENNETT, London. 
ON THE STOMATA IN THE FRUIT OF IRIS PSEU- 
DACORUS, LIN. — So many papers have been written on the develop- 
ment and structure of the stomata of plants that it might seem almost 
superfluous to contribute any further details to a subject on which 
our knowledge appears to be so complete. But the conditions 
which regulate the process of cell-division in a leaf (and it is in leaves 
that stomata have chiefly been studied) are not precisely similar to 
those which obtain in a growing fruit, and it is probably upon this 
fact that the peculiarities now to be described in some measure depend. 
Whilst in leaves the division of the epidermal cells, so far at least 
as the production of stomata is concerned, ceases at a comparatively 
early stage, this is frequently not the case in growing fruits, and 
Iris pseudacorus presents a striking example of stomatal formation 
extending over a considerable period of time. 
The epidermis of the ovary in a young bud consists of small, 
somewhat irregularly elongated cells from which the mother-cells 
of the stomata are cut off in the way described by Strasburger 1 for 
the leaf of this plant. The ovary does not however reach its full 
size until the bud is almost ready to expand, and if the epidermis be 
examined at this stage its cells clearly exhibit the properties of tissues 
still in a merismatic condition. 
If the flower be fertilized the ovary swells, and rapidly increases 
in size, and this process is accompanied, not merely by growth and 
extension on the part of the epidermal cells, but also by a very 
considerable increase in their number. As this takes place, certain 
cells become clearly marked off from those which surround them, 
both on account of their much smaller size, and also by their richness 
in protoplasmic contents. These small cells are the potential mother- 
cells of a fresh series of stomata, and their development may be traced 
in all stages (Figs. 6-13). Not all, however, of these cells appear 
actually to give rise to stomata, for in fruits of an advanced age they 
may be detected in various stages of arrested development. When 
1 Ein Beitr. zur Entwickelungsgesch. d. Spaltoffnungen, Pringsh. Jahrb. Bd. V. 
