Jan., 1 905 .J 



KNOWLEDGE & SCIENTIFIC NEWS. 



examined through a lens of about the same power as 

 they are intended to be viewed through, in order to see 

 whether they are worth proceeding with. The photo- 

 graphs are then cut into small squares with a diamond, 

 and can be mounted direct on to slides of the ordinary 

 form or to the flat end of the small Stanhope lenses, to 

 which they are generally attached. The slide or the 

 Stanhope lens must be warmed, and the mounting 

 medium is Canada balsam. Care must be taken that 

 the contact is perfect, and that the slide is free from 

 either air-bubbles or dust. 



Ne^v Regulator for CaLmbridge 

 Embedding-Bath. 



The Cambridge Scientific Instrument Co. have 

 brought out a new regulator for their well-known and 

 most convenient embedding-bath, which does away with 

 the former mercury regulator with its failings. The new 

 regulator was primarily designed to utilize an ordinary 

 paraffin lamp, where gas is not available. The hot air 

 travelling up a short chimney heats the water in the 

 bath. Suspended over the chimney by a lever is a 

 plate of brass serving as a sort of lid. This lever is in 

 contact with a bar of aluminium which is enclosed 

 inside the bath, and is stayed between similar bars of 

 nickel steel in such a way that it can only move 

 laterally, and in so moving raise or depress the 



111 



lever according to variations in temperature of the 

 bath. Any such movement of the lever therefore alters 

 the position of the lid, and consequently regulates the 

 amount of heat transmitted to the bath. Provision is 

 made for the primary adjustments. Though originally 

 arranged for a lamp (as illustrated) I think it would 

 be equally effective with a small burner, and I believe 

 the makers have adapted it accordingly. 



I would like to call attention to the fact that the 

 Cambridge Scientific Instrument Co. have just reduced 

 the price of the improved 1900 model of their well- 

 known Rocking Microtome to £3 iss., and have with- 

 drawn the older model altogether. For cutting serial 

 paraffin sections this microtome has now a European 



reputation, and needs no recommendation. It i^ in ii^c 

 in probably every large English laboratory, and the 

 reduction in price should largely increase its use by all 



classes of workers. 



Journal of the Quekett Club. 



1 he half-yearly issue of the Journal of Quekcll Micro- 

 scii/>ical Club, dated November last, contains the follow- 

 ing papers : — " The Genital Organs of Taenia sinuosa," 

 by Mr. T. B. Rosseter (illustrated); " .Some New .Sense 

 Organs in Diptera," by Mr. W. Wesche (illustrated); 

 the description of two new British Water-mites, by 

 Mr. C. D. Soar, and a list of the Spiders of the 

 Erigone group, by Mr. F. P. Smith. None of these 

 papers lend themselves to review, but the Proceedings 

 of the Club contain a rtsiimk of an interesting lecture 

 by Dr. E. J. Spitta on suiting screens for photo-micro- 

 graphy of stained bacteria in order to increase con- 

 trast, with reference to the value of the light for photo- 

 graphic rather than visual purposes. Dr. Spitta had 

 tested by means of a spectroscope the behaviour of 

 various orthochromatic plates to light of different 

 wave-lengths, and his paper is illustrated by a plate 

 showing the result, which deserves careful study by 

 photo-micrographers. 



Notes and Queries. 



Mounting Volvox, Larvae of Water Insects, &c. 



Mr. F. T. Perks, of Denmark Hill, would be glad to know 

 if there is any method of mounting Volvox, LarvEE, &c., so as 

 to preserve their natural colour. The ordinary methods of 

 mounting certainly fail to do this, and most zoologists would 

 either examine the objects alive or stain them in such a way 

 as to bring out some special feature. So far as the larvae are 

 concerned I think they might be narcotized by cocaine, then 

 killed with a J per cent, solution of osmic acid, and mounted 

 in 2i per cent, solution of formalin accordmg to Mr. RoLisselet's 

 method for Rotifera, but I could not say whether this would 

 prove practicable with Volvox, which is a particularly difficult 

 object to mount satisfactorily so as to show all the structure. 

 Full particulars of Mr. Rousselet's methods have been 

 frequently published; there is a very full account in Cross and 

 Cole's " Modern Microscopy." Perhaps Mr. I'erks will let me 

 know the result of his experiments, or I should be glad of sug- 

 gestions from other readers. 

 Use of the Petrological Microscope. 



Mr. J. F. I\. Green wishes to know of a book dealing with 

 the use of the petrological microscope. There is unfortunately 

 no book dealing with the subject from the microscopic stand- 

 point, even the largest works being strangely silent on the 

 matter. In the "Annual of Microscopy" for lyoo I 

 endeavoured to deal with the fundamental principles of the 

 subject in an article entitled "The Practical Applications of 

 the Polarizing Microscope," to which I may perhaps refer my 

 correspondent if he requires a brief rhumc of the subject. For 

 further information he might read Groth's " Physikalische 

 Krystallographie," or Dana's " Textbook of Mineralogy," or 

 Rutley's " Study of Rocks," and Cole's " Practical Geology," 

 which deal with the petrological and geological side, and inci- 

 dentally touch on the microscopical methods. I must warn 

 him, however, that the subject is one that requires study if it 

 is to be of practical service in petrology or crystallography. 



Echinus Spines. ^ 



Rev. W. Hamilton Gordon, Fareham.— Mr. Alfred Ueatn, 

 of Bury St. Edmunds, who kindly sent me the spines, informs 

 me that they are Echinus sphara, and that he found several of 

 them on the coast at St. Osyth, a village between Clacton-on- 

 Sea and Brightlingsea. 



[Communications and enquiries on Microscopical matters are invited, 

 and shouU be addressed to F. Shillington Scales, ''Jersey, St. 

 Barnibas Road, Cambridge.] 



