362 SUMMARY OF CURRENT RESEARCHES RELATING TO 



draught of the aspirator, a large number of particles must be carried past 

 without entering the aeroscope ; and if the power of the aspirator 

 exceed the force of the wind, it would tend to lift the light but 

 quiescent particles in the immediate proximity. 



The object which engaged Dr. Maddox's attention at the time was 

 to ascertain by cultivation whether the collected germs were capable 

 of germinating under the measures used, — in fact, whether they were 

 living or dead ; hence glycerine was discarded. It is gratifying to 

 see that M. Miquel intends to continue bringing his great patience and 

 ingeniiity to the experimental examination by cultivation, in flasks, of 

 the " Schizophytes de I'atmosphcre," the more important part of the 

 inquiry. The advantages he enjoys at the Park of Montsouris have 

 already yielded most interesting results. Although it is not likely 

 that we shall ever be able to exactly imitate the processes at work, as 

 temperature, moisture, pabulum, &c., which lead to i-apid development 

 of septic elements within a highly organized living being ; yet the 

 recognition of trustworthy cultivations out of the body is amongst 

 the first conditions for understanding the agency, whether hurtful or 

 otherwise, of the minute organisms which so largely surround us, 

 enabling us to test their properties by inoculations on the lower 

 animals at any stage of their cultivation. Still such studies will 

 require to be extended over a large area in different countries before 

 we shall be able to arrive at their real estimate in reference to disease, 

 whether of man or animals. 



Slip-cleaning Instrument.* — Mr. Searle brought this instrument 

 before the members of the Postal Microscopical Society at their last 

 meeting. It consists of a flat piece of wood 15 x 4 x ;! ii^ch. Along 

 each side of this and close to the edge is fastened a slip of wood 

 12 X ^ X ^ inch, thus leaving a clear space of 3 inches between them, 

 and in which the slips are arranged for cleaning. Two other loose 

 strips 14 X ^ X :j inch are now placed upon the ends of the glass, 

 and are each secured at one end by being slipped into a staple. That 

 portion of the wood on which the slip rests is padded with cloth. 

 The rubber for polishing the centre of the slips is made by glueing 

 two thicknesses of cloth on the end of a large cotton reel ; a piece of 

 washleather is stretched over the cloth and secured by being tied to 

 the middle of the reel. It is desirable to have two of these padded 

 reels, one to use with jiutty powder, the other to give the final 

 polish. 



"Opaque" Illumination by the Vertical Illuminator. — On this 

 subject Professor J. E. Smith remarks f that definition of surface (as 

 distinguished from " penetration ") is par excellence the legitimate as 

 well as the safest field for microscopical investigations of an advanced 

 nature over objects more or less opaque. 



" All attempts to illuminate objects by reflected light under high 

 amplifications had signally failed, until about five years ago, when 

 Mr. Geo. W. Morehouse, of Wayland, N.Y., made the important dis- 



* ' Northern Microscopist,' i. (1881) p. 68. 

 ^ Amer. .Tonrn. Micr., v. (1880) pp. 204-6. 



