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Supplement to ijte "Tropical Agriculturist." [February i, 1890 
sion or osmose, the cells immediately behind the grow- 
ing point deliver up part of their water to the younger 
cells of the growing point in front of them, and 
take water from the cells containing less protoplasm 
and more water, which in turn take water from the 
still older cells. And so this action of one oell con- 
taining much water, delivering up part of it to the 
next and younger cell containing less water, goes on 
till we come to the root-hair cells. These root-hair 
cells contain a thick sappy fluid saturated with 
dissolved nutrient substances, and so are enabled by 
the action of diffusion to take less saturated solutions 
from the soil. Now both the gaseous material and 
the liquid matter meet in the leaves — the crude sap 
travelling right through the plant from the roots : so 
that the leaf may be described as the laboratory of 
the plant, where the manufacturing goes on. Now 
let us enquire what chemical elements the plant re- 
quires in order to manufacture the organio matter to 
build up its tissues, in what compound forms the 
plant takes these elements, and lastly how, so far as 
we know, this manufacturing is carried on. 
(To be continued.) 
— ♦ 
LIFE -HISTORIES OF INSECTS INJURIOUS 
TO VEGETATION IN CEYLON. IV. 
By Aba. 
1. Order Coleoptera Beetles. 
1, Calanclra Oryzce, Linn. ; 2, larva ; 3, pupa, 
magnified. 
The Coleoptera or beetles form an exceedingly 
numerous and compact order. The beetles are mandi- 
bulate insects having four wings, the upper or first 
pair of which called the wing-oases or elytra are usually 
horny or leathery and not at all suited for flight . 
They form a " sheath " or covering for the larg e 
membranous hind wings which are folded beneath 
them when at rest. The inner margins of the wing 
cases touch] and form a straight suture down the back 
when closed. The head is furnished with large eyes, 
jaws moving transversely, and with horns (antennas) of a 
great variety of shapes. 
A great many of the beetles are remarkable for their 
brilliant oolours or singular shapes. A Oeylon speci- 
men the "Ran Kuruminiya" of the Sinhalese is of a 
beautiful metallio green colour with yellow spots, The 
beetles have usually such a strong family likeness 
that they are seldom likely to be mistaken for insects of 
the other orders. 
At present nearly 100,000 species of beetles are 
known to exist ; these are mostly terrestrial but a few 
live in water, and the hinder legs of these are often 
flattened and oar-like in shape, and fringed with hairs. 
Many of the beetles are very injurious to vegetation 
particularly in the larval stage as the [cockchafer, wire- 
worm beetle (Tokka, Sinh,) &c. Some prove eminently 
useful by preying upon caterpillars, plant lice, and 
other destructive insects. Others aot the part of 
scavengers by removing carrion, dung, and other filth 
upon which they subsist. A few of the beetles 
(Caniliarid.cz) are used in medicine for blistering and 
other purposes. 
Thelarvce of the beetles are usually fleshy grubs with 
scaly heads furnished with jaws (the grubs found in 
dung heaps &c). They are usually provided with six 
legs, but are sometimes legless or apodous. 
The pupce are " necromorphous " or mummy-like. 
The head is bent forwards and the different organs of 
the future beetle enclosed in separate coverings are 
laid along beneath the breast and abdomen, with the 
pupa-skin closely enveloping the whole. The pupa 
are inactive, whitish in colour and resemble the perfeot 
insect in shape. Some of the beetles assume the pupa 
state in a cell of agglutinated earth or other matter, and 
the often fully-developed insect remains inactive for a 
considerable time before quitting its cell. 
It is beyond the scope of this series of articles to 
enter more fully into the description of the Oolioptera ; 
the reader is therefore referred to the works of Kirby 
and other entomologists for a fuller description of this 
and the other orders of insects. 
I will now proceed to give the life-histories of the 
Coleopterous insects that are commonly injurious to 
vegetable productions, as I shall the other insects under 
the different orders. I shall begin with the rice weevil 
(Calandra oryz<£), the gulla of the Sinhalese, an insect 
well known to my readers as occurring in all kinds of 
rice. 
The description which follows is partly the result of 
the writer's own observation and partly gathered from 
" An Account of the Wheat and Eice Weevil in India " 
by Mr. E. O. Cotes of the Indian Museum, and other 
sources. But it is not to be considered that the account 
is at all complete ; on the other hand there is much in- 
formation wanting especially with regard to prevention 
and remedies, and to whether the attacks of the pest 
are confined only to stored grain as at present supposed 
or occurs in the field and elsewhere. It is w orthy of 
note here thatf the weevil is not known to attack rice in 
the husk (paddy) when stored or otherwise. 
Mr. Cotes thus notices the occurrence of two distinct 
species of the weevil : — " Stored grain in different 
parts of the world is liable to be attacked by two dis- 
tinct species of weevil, viz., Calandra (Silophilus) gra- 
naria and Calandra (Sitophilus) oryzce. These two 
species are so much like each other and have habits 
so nearly identical, that no 6tudy of the subject would 
be complete without taking both species into consider- 
ation. 0. granaria is supposed to have been introduced. 
