NOTES AND MEMORANDA. 
Erratum.—Our esteemed contributor, Mr. W. S. Kent, 
desires us to make the following correction in his paper pub- 
lished in our last number. On page 397 of Vol. X, line 10 
from the bottom, for “‘ parasites of spicula” read “ fascicles 
of spicula.” 
Charts for recording Absorption Spectra.—Mr. John Brown- 
ing of the Minories has, after much trouble, succeeded in 
getting a sheet printed in colours, giving seven coloured 
spectra of the size and appearance obtained by his micro- 
spectroscope. The position of the chief solar lines is marked, 
and the position and intensity of absorption bands may be 
put in with pencil or paint-brush. The sheets are sold 
at a very small price, Mr. Browning’s object being to encourage 
the recording of observations. This he has further facilitated 
by his illuminated moveable scale, which he now fits to the 
micro-spectroscope. 
Cheap High-power Objectives.—Mr. Baker of Holborn has 
become agent for the supply of the objectives made by 
Gundlach, of Berlin, and we have been favoured by Mr. 
Curties with several for examination. The glasses are re- 
markably cheap and well worth the money which they cost. 
The 4rd costing one guinea is a useful glass for general 
work; the 4th, at a little less than two pounds, is excel- 
lent, ,and fully equal to all requirements in histological 
work. At three pounds thirteen, a dry ;;th, or an immersion 
=!;th with corrections, is sold. These glasses require 
picking over before purchase, since some, especially among 
the ;1;th immersions, are not so good as others. The +th 
with corrections, or at sixteen shillings less if without cor- 
rections, is the most to be recommended in the series. It 
is, for histological work, and for all purposes, but the resolu- 
tion of the very finest tests, as useful as any ~;th by our 
best makers. It is necessary now for the medical student 
and the naturalist to have higher powers at hand than the 
one quarter with which most are supplied. The difficulty 
of expense is removed by the low price of Gundlach’s 
glasses, and now that Mr. Hartnack has been obliged to 
