ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
555 
by you previous to the formulation of our agreement, the same proposal 
would have been made by us. We only stipulate that you should, for 
the present, exclude your personal experience regarding methods and 
means from publicity, and that in your publication you mention that 
the firm of C. Zeiss, in Jena, has undertaken to render your experiments, 
if possible, available for the requirements of practical optics. (The 
numerical values of /x and A /x very nearly agree with the result obtained 
by spectrometric measurement by Dr. Abbe years ago with respect to 
several varieties of natural opal.) ’ 
These extracts will show Mr. Wright how much truth there is in 
his statements with respect to the monopoly of the German house. I 
emphatically endorse his remark ‘ the sooner such a peculiarly German 
method is understood by microscopists the better.’ True, if he means 
the better for the firm of Zeiss. 
In order, however, that Mr. Lewis Wright may be freed from any 
vestige of a doubt, the firm of Zeiss offer to place at his command all 
communications which they have received from Mr. Brun, and they offer 
him a premium of 1000m. if he will pledge himself to supply within 
the period of one year 160 grammes of optically useful opal produced 
after the method of Mr. Brun. 
If Mr. Wright be not equally a ‘ baby ’ in technical processes, as 
he confessedly is in matters pertaining to patent law, he will find it 
an easy task to merit the premium offered to him, and to enrich the 
stores of technical optics by such a valuable material.” 
To this letter Mr. R. Kanthack adds the following: — “The above 
letter of Dr. Czapski (which, by the way, is a translation, and should, 
in fairness to the original writer, be read as such) will no doubt 
be sufficient to remove Mr. Lewis Wright’s doubts ; but it may not 
be uninteresting to him to hear that within the last eighteen months 
respectable quantities of fluorite were offered me in my capacity as 
agent of the firm of Zeiss. The fact, however, that the price offered 
almost ridiculed [sic] the price expected — so much so, that in one case it 
was thought more profitable to utilize the fluor spar for garden de- 
corations — agrees but imperfectly with the allegation that the firm 
of Zeiss is bent upon securing all existing fluorite mines. Summing 
up Dr. (Jzapski’s explanatory statements, it would appear that for the 
construction of apochroraatic lenses fluorite is ‘ useful,’ but mathe- 
matics ‘ indispensable.’ I may here mention that it is only due to 
want of appreciation of the mathematical principle of apochromatism 
that the terms ‘ semi- apochromatic lenses ’ and ‘apochromatic glasses’ 
(the latter as applied to the raw material produced by the Abbe-Schott 
process) retain their scientific sound, when in reality they can claim 
no more meaning than that attachable to trade advertisement.” 
£. Technique.* 
Zimmermann’s Botanical Micro-technique. j — We have here a 
much-needed handbook of microscopical preparations, chemical reactions, 
* This subdivision contains (1) Collecting Objects, including Culture Pro- 
cesses; (2) Preparing Objects ; (3) Cutting, including Imbedding and Microtomes; 
(4) Staining and Injecting: (5) Mounting, including slides, preservative fluids, &c. ; 
(6) Miscellaneous. 
f ‘ Die Botanische Mikrotechnik,’ von Dr. A. Zimmermann, Tubingen, 1892, 
x. and 278 pp. and 63 figs. 
