1885.J 



MICROSCOPICAL JOURNAL. 



29 



aperture in the funnel opening be- 

 neath. The clock, being allowed to 

 act for an hour, brings the line of the 

 next division into registration at mid- 

 day. The instrument being attached 

 to an aspirator and air-meter, the air 

 is sucked through the funnel, leaving 

 the germs, bacteria, fungi, &c., on 

 the glass as it traverses centrally 

 across the orifice of the funnel at the 

 rate of an hour between each gradu- 

 ation. This is a most useful and in- 

 genious instrument, but rather costly. 



There is another of a somewhat 

 similar function, consisting of a bell 

 glass inverted over another with a 

 ledge, which can be filled by vaseline, 

 glycerin, or oil to render the inner 

 space air-tight, whilst a disc divided 

 into separate spaces and covered with 

 a sticky material is made to rotate by 

 a drum clock beneath, so that the di- 

 visions are brought opposite to a long 

 slit ground out in the upper part of 

 the bell glass for the air to enter. At 

 the conclusion of the experiment the 

 glass plate is removed and examined 

 by the use of the microscope, though 

 the naked eye can detect differences 

 between the hourly deposits. 



There is another small nickel-plated 

 aeroscope attached to an ordinary 

 water aspirator ; a portable aspirator, 

 consisting of two large glass jars, for 

 drawing over a moderate but definite 

 quantity of air, and an ordinary water 

 aspirator ; also a mercurial one for 

 the drawing over fractional portions 

 of air. Likewise on two pillars at 

 the corners of the table are the modi- 

 fied forms of the Maddox aeroscope, 

 as used at sea and on land. There 

 are different forms of sterilizing appa- 

 ratus both for hot and cold filtration, 

 and several flasks with readily altera- 

 ble fluids which have thus been steril- 

 ized, and remain perfectly clear. 

 There are some useful little glass cul- 

 t u r e cells — a modification of Van 

 Tieghem and Lemmonier's cell — and 

 delicate pipettes for infecting the drop- 

 let of sterilized fluid placed on the 

 thin cover glass for microscoipc ex- 

 amination under culture. 



To the exhibits is added a very 

 valuable list of disinfectants, and such 

 articles as prevent the rejuvenescence 

 of bacteria in readily-putrescible fluid, 

 the biniodide of mercury heading the 

 list ; 0.025 of a gramme preventing 

 the putrescence of one litre of neutral 

 beef broth — a thousand times less in 

 weight than what is required of cry s- 

 talized phenic acid. This list alone 

 suffices to particularize Dr. Miquel's 

 patience and industry. (See La Se- 

 7)1 a i 71 e ISTedicale for 30th August, 

 1883.) It may be stated that the mil- 

 dews, which are constant in the air, 

 interfere largely by their rapid growth 

 in the culture chamber if the sterilized 

 liquid be at all acid ; hence care is 

 needed to neutralize, or even render 

 slightly alkaline, the liquid in use. 

 Dr. Miquel has raised an important 

 point, much ovei'looked, as to the 

 death and reviving points in different 

 liquids, and the same liquids at differ- 

 ent degrees of density. There are 

 also M. Certes' exhibits of water 

 analysis by coloring the different liv- 

 ing organisms. 



At the same table are other exhib- 

 its, and notably some microscopes by 

 Verrick, and large model microscopes 

 by Nachet, accompanied by a pho- 

 tomicrographic camera. This differs 

 from any we are acquainted with, in 

 that it contains a side tube carrying a 

 prism, used in the examination and 

 placing of the object, and which al- 

 lows of the prisin being withdrawn 

 out of the field prior to exposure, so 

 that a person seated at the side can 

 manipulate the apparatus with ease. 

 The camera is of a fixed length, and 

 carries at the side the focussing rod, 

 connected by a pulley and cord with 

 the fine adjustment. We rather ob- 

 ject to the position of the focussing- 

 rod, which, like that made by Siebert, 

 we fear may be somewhat in the way. 



We must not longer linger over the 

 interesting objects of this exhibit, 

 which we heard a gentleman say was 

 one of those of the greatest interest 

 in the Exhibition, but pass to the table 

 of M. Pasteur — a name too widely 



