240 
IOWA ACADEMY OF SCIENCE Voi,. XXIX, 1922 
In this preliminary report are recorded the conditions found 
in a few of these leaves, Sage ( Salvia officinalis ), Honey-suckle 
( Lonicera Sullivantii ) , Bryophyllum sp., Red Clover ( Trifolium 
pratense), Horse-radish ( Nasturtium armoracia), Pittosporum sp. 
As may be noted there are included forms of diverse habitat and 
the series involves both herbaceous and woody plants. Included 
with plants growing here are Pittosporum , with firm evergreen 
leaf, mailed to me from Santa Monica, California, by Mr. N. D. 
Knupp ; and also the thick leaved Bryophyllum cultivated in plant 
houses. With one exception the leaves had been wounded through 
natural causes and were from plants growing out of doors. The 
Bryophyllum leaf was from a plant in the green house which had 
been wounded 72 days before collection. The cicatrices shown 
in the figures are all apparently mature. All figures are drawn 
to common scale. 
Following the injury of a leaf there is probably a temporary 
covering over the open edge due in large part to the collapsed 
and dried mesophyll cells which die back for some distance from 
the cut edge. This is often aided by over- folding of epidermal 
layers, particularly in the case of the softer leaves (figs. 1, 3, 4, 5). 
