112 SUMMARY OF CURRENT RESEARCHES RELATINa TO 



paper being previously sterilized for an hour at the temperature of 

 110° C. The air thus set in motion and entering through the narrow 

 slit strikes the paper, which is marked at the time of starting and 

 closing the experiment, and lasts twenty-four hours ; whilst the current 

 of air is made to traverse the space at the rate of 30 to GO litres per 

 hoiir according to circumstances. The drum with its paper is then 

 placed in a second glass shade for incubation of the bacteria. Both 

 vases have the air saturated \\itli moisture from a sponge wetted with 

 a solution of bichloride of mercury placed inside. Special precautions 

 are taken in smearing the junctions with vaseline, and the mercury 

 in whicli the shade stands with asceptic glycerin. 



For use stout paper coloured upon one or both sides according to 

 the object in view is preferred for covering with the lichen jelly. 

 Dr. Miquel has jDrepared this for the last two years by dissolving 

 from 25 to 30 gr. of Fiicus crisjms (Irish moss) in a litre of beef 

 broth, then strained, neutralized, boiled for a short time, and filtered. 

 To prevent loss by evaporation a jelly of the lichen is made with water 

 and dried, and this, to the amount of about 1 per cent., is added to the 

 broth. The prepared jelly melts at about 55^ to 60^ C, thus serving for 

 the incubation of bacteria requiring high temperatures. Sterilization by 

 several boilings at short intervals is not relied upon. Coloured paper, 

 of a blue tint preferred, is spread with the warm neutral lichen broth to 

 the depth of two to three mm., then dried rapidly in a stove at 40° C, 

 and is then capable of indefinite preservation. For use it is heated 

 in vapour at 110° C, without any deterioration, and its hygi'ometric 

 quality can be increased or restrained as desired, or it can be made 

 alkaline for bacteria. 



For the analysis of rain, Dr. Miquel has invented a special 

 apparatus, his " Udobacteriemetre," consisting, in brief, of a glass 

 shade with its neck fitted with a stopper through which is passed the 

 long stem of a metal funnel, that delivers by droplets the rain caught, 

 and projects them upon the nutritive paper arranged as a very wide 

 truncated cone, which is rotated at some speed by clockwork beneath. 

 The droplets are carried by the rotation a little way along the 

 sterilized paper cone, moistening the lichen surface of the paper in 

 their course at different i)oints, no troublesome liquefaction taking 

 place as with ordinary gelatin. The cone of paper at the end of the 

 experiment, like the former, is placed in the incubating stove with its 

 damp atmosphere, and afibrds excellent results. 



The paper has a third use. In a small precipitate glass with a 

 foot, and closed by an emery-ground tubulated cap, like Pasteur's 

 flasks, a little wetted cotton is placed. Through the tube is jiassed 

 a platinum wire, crooked at the end to support a band of the nutritive 

 paper covered on both sides, about 3 cm. wide and 8 long, equivalent 

 to about half a decimetre square surface. All is sterilized at 110° C, 

 and then weighed to a milligramme. The mouth is now uncapped, 

 the paper plunged for one to two minutes into the water to bo 

 analysed for the difiierent organisms, then introduced into the 

 eprouvette, and reweighed. If the water be impui'c, it is not long 

 before small spots show the deposition and growth of the microbes, 



