THE TROPICAL AGRICULTURIST. [February i, i888- 
HOW DRAINAGE AFFECTS VEGETATION. 
It' a sample of common soil is examined with a 
magnifying glass, it is found to be composed of 
numerous fragments of minerals of various kinds, 
humus, muck, and often of undecomposed vegetable 
or animal matter. These fragments are very irregular 
in form and size, and are in contact only at their 
more prominent corners. They might be compared 
to a mass of coal of various sizes mixed 
together, the difference being that the fragments of 
coal are all of one substance, whereas the 6oil is 
composed of various substances. Now we know that 
if we pour water over a basket of coal, a thin layer 
of water adheres to each fragments and the rest 
passes off through the meshes of the basket. Just 
so, when a soil is wet by the rain, each tiny fragment 
is surrounded by a thin film of water, and the rest, 
if the soil is in a normal condition, filters through 
and flows away. As the fragments of the soil arc 
very much smaller thin those of the coal, while the 
film of water that adheres to the particles is per- 
haps just as thick, it follows that the amount of 
water, retained by a given bulk of soil is vastly greater 
than by an equal bulk of coal. 
Suppose we put the coal in a light pail instead of 
a basket, and then pour on water. Of course the 
water fills the interstices between the fragments and 
the air is all driven out, except a few bubbles that 
become entangled. This is precisely what happens 
when heavy rains fall upon a soil that has an im- 
pervious clay subsoil. The spaces between the particles 
become almost all filled with water, and the air with 
the oxygen it contains, is mostly driven out. 
Botanists tell us that the root-hairs, that supply 
the roots with water and its nourishing substances in 
solution, cannot live without oxygen. If the oxygen 
is shut away from roots, therefore, the roots will 
die. In dying they not only injure the plant to which 
the;' belong, but the matter of which they are formed 
soon undergoes decomposition, and generates gases 
which are injurious to other healthy root-hairs in 
the neighbourhood. 
To be sure, the rain-water, as it falls upon the soil, 
is charged with oxygen, but in passing downward a 
part of this is filtered out ; another part unites with 
organic matter in the soil, so that after the water 
remains for a time it becomes deficient in the life- 
giving oxygen. Hence it is that when a soil is filled 
with water the roots of land plants cannot live in it 
in a healthy condition. 
"When, however, we provide an outlet for this surplus 
water, it slowly flows away, and in doing so the 
sir forces itself in from the top of the soil, and the 
roots are abundantly supplied with oxygen. From 
lime to time rains come, and, temporarily filling the 
cavitips of the soil, drive out the air within them 
that his given up a part of its oxygeu. As this 
water passes off through the drainage, fresh air en- 
ters again, and thus the roots are kept supplied 
with oxygen.— Prof. E.~S. Goff, of N. E. L. Station, 
in Philadelphia Weekly Press. 
THE STUDY OF VEGETABLE PHYSIOLOGY. 
A great change has of late yeirs come over the sub- 
ject /f botanical teaching in this country. Up till re- 
cently much stre-s was laid upon the investigation of the 
outward conformation of flowering plants especially, 
and upon their orderly cl iss fication according to 
t>ie natural system. Minute anatomy, such as re- 
quire- the aid of the compound microscope, and of 
ch raical reagents, was less attended to, while vege^ 
table physiology or the investigation of the mode 
of ac'ion of living plants was almost entirely ne- 
glecterl. The lower orders of plants, so called, 
were little, studied — so little, indeed, that even A. 
Berkeley thought it requisite to state in his cele- 
brated Introduction to Cryptoyamic Botany, that the 
«t ii' lent of cryptogams need not blush for the sub- 
let of his choice ! Of late years, chi'fly owing to 
the introduction of German methods of tuition, and 
t > the mode of instruction by means of specimens 
/•elected ai> types of each principal group, matters 
have greatly altered. The system of instruction 
from type specimens was introduced into this coun- 
try by Huxley and Rolleston in the case of animals, 
and adopted by Dyer in the case of plants. The 
plan, in general terms, consists in the lecturer de- 
tailing to his audience the salient features of each 
group, illustrating them by diagrams or black-board 
illustrations, and then placing in the hands of the 
pupils, specimens of the plants, in order that they 
may for themselves work out the details sketched in 
outline by the lecturer. The pupil, according to 
this method, is compelled, not only to use his wars 
and attend to what the lecturer or the text-book 
may tell him, but also to prove its correctness by 
his own individual extertions. The efforts of the 
student in following out this plan, and especially 
the necessity incumbent upon him of making draw- 
ings of what he sees, are especially valuable as dis- 
cipline ; and for those who wish to gain a general 
idea of the whole subject no better plan can be 
conceived. For the acquisition of special knowledge, 
however, there is nothing to equal the preparation 
under the master's eye, of a comparative monograph 
of a 6ingle group. It is a question whether the 
pupils of the present day, though better trained as 
general biologists, are as likely to turn out such 
good botanists and naturalists as were their prede- 
cessors, for once out of sight of their "type" they 
are more at 6ea than were their predecessors, who 
learnt their grammar systematically. 
Vegetable physiology proper — a subject of profound 
importance to the cultivator — still lags in arrear 
in this country. We have had our Grew, our Hales, 
our Robert Brown, our Thomas Andrew Knight ; 
but since the time of the latter— if we except 
Darwin, who is exceptional in all ways — we have had 
few men who could claim to occupy a foremost rank 
as vegetable physiologists. The fact is, that vege- 
table physiology, apart from the investigation of the 
miscroscopic structure of plants has become chiefly 
a matter for students of physics and of chemistry, 
and students of these sciences have preferred to 
study the abstract sciences in their laboratories ra- 
ther than follow up their applications in the living 
plant. Chemists, indeed, have told us a good deal 
concerning the chemical constitution of dead plants. 
They cremate them and then study their ashes — an 
odd method, it would seem, of studying the life- 
action of plants. Combined, however, with practical 
observations and well devised experiments in the 
laboratory and in the field or garden, such a method 
renders invaluable assiftmce. We earnestly hope, 
therefore, that the jounger school of botanists now 
coming forward will see the great need there of 
their services, and actively take upon themselves 
the task of unravelling the problems of plant life. 
As a precious aid in this direction we may call 
attention to Professor Marshall Ward's lately pub- 
lished translation of Sachs' Lectures on the Physiology 
of Plants. * Those who are familiar with the Ex- 
perimental Physiology of the celebrated German 
author and with his Lectures, as here translated, 
will know how greatly superior those works are in 
grasp and lucidity to his Te.rt-hook, and hence stu- 
dents will feel specially grateful to FroFessor Ward 
for this translation of the Vorlesunyen, and for the 
admirable way in whi< h he has accomplished it. — 
Gardeners' Chronicle 
AGRICULTURE IN SOME OF ITS RELATIONS 
WITH CHEMISTRY. 
Agriculture in soma of its Relations with Chemistry 
By F. H. Stores. Two Vols. (London : Sampson 
Low, Marston, Searle, and Rivington , 1837.) 
This work, by ihe Professor of Agricultural Chemistry 
at the Harvard Uuivdrsity, is based on a course of 
lectures delivered annually by the author. It is 
addressed to students of agricul ture and persons fond 
* Lectures on the Physiology of Plants. By Julius 
Von Sachs, translated' by H. Marshall Ward, Pro- 
fessor of Botany in the Forestry School, R. I. B 
College, Cooper's Hill- Oxford : Clarendon Pre?«. 
