550 
ON THE ANATOMY OF DREGS. 
The origin of the officinal nut-gall is well known. A peculiar insect (Dlplo- 
lepis Gallx tlnctorife) infests a single species of oak {Querciis infectoria) ; the 
female punctures the epidermis of the young soft shoots and deposits an egg in 
the cavity; an excrescence is rapidly formed and increases in size until it be¬ 
comes the fully formed gall, the egg meanwhile having passed into the pupa 
stage. If the galls are gathered and dried before the insect has made its escape 
they have a bluish exterior, and the cocoon may be found filling the central 
cavity, but if they have been left on the tree too long a neat round perforation 
may be noticed marking the spot where the insect, arrived at maturity, has 
eaten its way out, and the galls then have a yellowish-brown colour. A section 
of a nut-gall examined by means of a pretty high magnifying power shows how 
completely vegetable is its structure. Nearest the central cavity a series of 
cells are observed (first pointed out by Gruibourt) containing starch. An inner 
wall composed of a number of irregular layers of hard cells nearly filled with 
secondary deposit occupies the space surrounding the cavity, and the remainder 
of the gall is made up of a regular tissue composed of angular cells, large near 
the centre, small and compact towards the periphery. Here and there may be 
observed fragments of fibro-vascular bundles, traversing the tissue in a sinuous 
course. 
In bringing these remarks'to a conclusion, it is needless to frame excuses for 
the incompleteness of what has only been intended as a rough sketch, and 
treated in a suggestive rather than detailed fashion. It would have been easy 
to have written a simple criticism on Professor Berg’s ‘ Atlas,’ but we have 
indulged a hope that by a few broad indications of the scope of microscopical 
study in connection with organic medicines, some interest in it might be 
awakened amongst those who are still young, and, in the common sense of the 
term, still students. There can be no better wish for them than that they may 
ever remain students. A microscope, thanks to the popularity of the instru¬ 
ment, is no longer an expensive luxury, and for a few shillings the accessories 
required for the preparation and mounting of specimens may be purchased. Let 
it ever be borne in mind that good work does not depend on costly, still less on 
showy apparatus, but on perseverance and accurate observation. To observe 
well is a faculty that must be learnt. Schleiden has said that “ seeing is a diffi¬ 
cult art—if difficult under ordinary circumstances, how much more so, when 
deprived of the assistance in reading appearances yielded by comparison with 
surrounding objects. There is no aid to accuracy so serviceable as drawing,^' 
especially drawing in outline with the camera lucida. The limited amount of 
mechanical skill required for its practice in ordinary cases, may be attained by 
almost any one who will devote a little time and pains to its acquirement. 
Sketches thus made are of far greater value than any written notes, both in the 
stronger impression they produce upon the mind at the time, and in the facilities 
they offer for future reference. 
We may now leave the subject in the hands of our readers. 
^ Apropos of seeing and drawing ” the following has (he seal of much experience:—“For 
I am nearly convinced that when once we see keenly enough there is very little difficulty in 
drawing what w^e see ; but, even supposing that this difficulty he still great, I believe that the 
sight is a more important thing than the drawing; and 1 would rather teach drawing that 
ray pupils may learn to love Nature, than teach the looking at Nature that they ma}’ learn to 
draw.”'— JRnskin, ‘ Elements of Eraiving,'' Fo'eface, p. xi. 
