220 REVIEWS. 
optics was either not so well understood as it is now, or its prac- 
tical application was not so fully comprehended as it is im our 
times. But the knowledge of microscopy, as a science, has not 
advanced so rapidly as the means for its attainment. About 
thirty years ago the only good lenses were of foreign manufac- 
ture. In our younger days Munich had the reputation of manu- 
facturing the best magnifying glasses. In these days we believe 
that no one acquainted with the subject doubts the immense 
superiority of English microscopical instruments. 
In the work before us there is a very succinct account of the 
elementary principles of optics, such as are essential to a com- 
prehension of the microscope itself. Another portion contains 
a description of different kinds of microscopes; the third gives 
an account of accessory apparatus, chemical re-agents, ete., ne- 
cessary for microscopical investigations in botany. We are glad 
to see that microscopes are now to be obtained at a cheaper rate 
than those manufactured by Ross, whose instruments, though of 
first-rate excellence, are generally too expensive to suit the means 
of the majority of botanists. A very useful form of microscope 
is represented in the frontispiece of this work, which may be ob- 
tained at a moderate price. 
We quote the following passage on axillary buds, as a speci- 
men of the style, etc., of the work :— 
The avillary bud consists at first of a small conical protuberance, 
which afterwards becomes elongated, and forms what may be called the 
bud-stem ; the rudiments of leaves originate under its apex, and in those 
cases where the bud does not immediately become developed into a branch 
or leaf, these rudiments ultimately form scales. Under the protection of 
these scales the punctum vegetationis rests for a period, after which new 
leaves are formed beneath it, which either contimue covered by the scales 
during the winter, or break out immediately and complete their develop- 
ment, as in the case of what are called the second shoots of trees. In the 
leaf-buds of annuals, which are immediately developed, scales are seldom 
found. Flower-buds cannot at first be distinguished from leaf-buds. 
‘With another quotation we must conclude our notice of this 
useful book. 
The pollen of the Conifere and Cycadee, if once dried, never becomes 
sufficiently saturated to enable the observer to come to any conclusion as 
to the division of its pollen-cell. This investigation, therefore, can only 
be undertaken with fresh pollen. It is then seen that the Cycadee of our 
