IIl.—Histological Studies in the Artemisia Formation 
BY RAYMOND JOHN POOL 
TABLE OF CONTENTS 
Introduction : : I 
The region in which ie Geld ended were made 3 
Material and methods 3 
Outline map 4 
Soil structure, water content, dhiiante 5 
Precipitation table 8 
Structural studies 8 
Water storage tissue. ; ; ; : : : ‘Saae 
Summary ; : : 3 : , : ‘ Tea 
Literature : “ é ; ‘ : : : 120 
Explanation of sities Rigen: shoe 
INTRODUCTION 
Many investigators have written on the subject of leaf histol- 
ogy and morphology in general, and a few have, in addition, 
touched upon the physiological significance of structures found 
during the progress of the study. Among these writers are Ha- 
berlandt, Pick, Stahl, Bonnier, Wagner, Hesselmann, and Clem- 
ents. Most of the work, however, has been purely histological 
or morphological with little or no reference to environic forces. 
But in these later days of the development of the new ecology: 
those forces or factors which have been potent in the evolution 
of plants and which are moulding plants today have come under 
careful observation and study, not only from the qualitative point — 
of view, but also from the quantitative standpoint. Among the 
most important of these studies is the one by Dr. E. S. Clements 
on The Relation of Leaf Structure to Physical Factors, in which 
UNIVERSITY StupiEs, Vol. VIII, No. 4, October 1908. 
AII 
