116 



THE AMEKICAN MONTHLY 



[June, 



A rheostat is also provided to regu- 

 late the strength of the current. The 

 apparatus is very complete and well 

 devised. 



Besides the illuminating apparatus, 

 the stage is provided with a spiral of 

 platinum wire through which a cur- 

 rent may he passed to heat the air 

 which passes up through the opening 

 in the stage. In this way the slide 

 and specimen under examination are 

 heated to any desired temperature. 

 A method of measuring the tempera- 

 ture of the object is also described. 



The arrangement for photomicro- 

 graphy with two battery cells is very 

 attractive, as it seems so exceeding- 

 ingly simple and convenient. The 

 lamp may be attached to the stand in 

 place of the mirror, or it may have an 

 independent support with joints per- 

 mitting of pi'oper adjustment. In 

 practice it seems to be eminently suc- 

 cessful up to magnifications of 300 

 diameters, but the exposures for such 

 a power require to be rather long — 

 about ten minutes or more. 



For microscopical work in summer 

 the electric light possesses great ad- 

 vantages, and when it is considered 

 that a couple of Bunsen cells will suf- 

 fice to give the necessary current, it 

 would seem well worth while for 

 dealers in microscopes to provide the 

 apparatus, so that one need not await 

 the developments so confidently antici- 

 pated in electric lighting. The ex- 

 pense cannot be very great, and to be 

 able to work without suffering from 

 the proximity of a lamp, which is 

 like a furnace in midsummer, would 

 be a great boon to all who use the 

 microscope. 



The second article to which we 

 have referred is by Dr. Max Flesch 

 It treats of the value of the electric 

 light for microscopical use, but fur- 

 ther reference to it must be deferred 

 until next month. 



Desmids of the United States. 

 — Our reference to Mr. Wolle's work 

 on the desmids of the United States 

 was written before a copy of the book 



had reached us. Having since re- 

 ceived a copy and given it a careful 

 examination, w^e can only say that it 

 far exceeds our expectations. The il- 

 lustrations especially are exceedingly 

 good and remarkably true to nature 

 as regards color. Our examination 

 has not been so critical as to i"eveal er- 

 rors in the text, if such there be — and 

 it is scarcely possible that the book is 

 perfect — but we can safely say that the 

 work has been very carefully done. 



We understand that only a small 

 edition has been printed, and that the 

 demand for copies has already been 

 unexpectedly large. To be sure, the 

 edition is not exhausted yet, but we 

 would not advise much delay in send- 

 ing orders. The book is really s6ld 

 very cheap, and the price shoukl be 

 raised after a short time. 



Preparing Anthers. — The ordi- 

 nary method of preparing the cells of 

 anthers for examination is long and 

 quite unsatisfactory. It consists in 

 macerating the anthers in water, long 

 and careful rubbing or trituration, 

 and thus obtaining some shreds of 

 the tissue showing the fibrous cells 

 forming their walls. Mr. J. Rata- 

 bone has described* a simpler meth- 

 od. The anthers are placed in alco- 

 hol of ^\^^ per cent, for about five 

 minutes, triturating _^r(?^5o modo, and 

 then in distilled water. In this way 

 the cells open as by enchantment, the 

 pollen-grains are easily detached, and 

 air-bubbles give no trouble. They 

 are presei^ved in glycerin. 

 o 



Schroder's Camera Lucida. — 

 The new camera lucida which was 

 so highly commended in these col- 

 umns some time ago is now, as we 

 learn from an advertisement in Sci- 

 ence Gossips offered for sale at 455'. 

 (about $10.50) by Messrs. Ross & 

 Co., of London. We give this infor- 

 mation for the benefit of numerous 

 subscribers who have made inquiries 



* Soc. Beige de Micr., Bull, des Sdances, 

 VII, cxli. 



