M'Weeney— 0» a Method of Preparing 8chizomycetes. 167 



bj B. pyocyanens. The beautiful greenish-yellow tinge which per- 

 meates the gelatine, in, or on, which the fluorescent water-bacilli are 

 grown, appears on potato as a dirty yellowish brown. A form ap- 

 parently intermediate between the yeast-fungi and the Torulas, 

 known to the Grermans as Rosahefe, forms a beautiful pink colour. 



A collection of permanent preparations of the various chromo- 

 genic organisms on appropriate substrata, would certainly form 

 an attractive and beautiful feature in our natural-history museums. 

 Although we have numbers of specimens illustrating the pigment- 

 producing powers of the higher plants and animals, I am not aware 

 that, in the Dublin museums at least, there are any preparations 

 illustrating this curious power as exercised by the lowly Schizomy- 

 cetals. 



I now come to the last portion of my subject : a short state- 

 ment of the advantages to be gained by the acquisition for our 

 museums of such collections of permanent bacterial preparations 

 as that which I have laid upon the table for your inspection. 

 These advantages may be thus briefly summed up : to the 

 unskilled or general public, the unusual appearance of these 

 specimens is in the highest degree calculated to excite interest; 

 and, in my view, one of the chief functions of a public museum 

 is, by exciting interest in the specimens exhibited, to lead the 

 observer to procure instruction. Correct ideas on the role of these 

 lowly organisms are very valuable, for they would naturally lead 

 their possessors to the practice of greater cleanliness and a more 

 intelligent hygiene. To educate the people on these points would, 

 in my opinion, be very desirable ; knowledge of the nature of 

 putrefaction, and correct appreciation of the danger of filth, might 

 go some way to remove that reproach of uncleanliness with which 

 our people have — and not unjustly, I fear — been branded. To 

 the trained observer or specialist, the importance of having such a 

 collection to refer to, would be almost inestimable. The resem- 

 blance of individuals belonging to different species, is often so 

 great as to mislead the most experienced. The best workers will 

 decline to say, for example, whether a given specimen, viewed 

 under a magnification of 1000 diameters, is the typhoid bacillus, or a 

 perfectly harmless water- saprophyte. It is the sum-total of bio- 

 logical and cultural characteristics which form the criterion ; and a 

 large amount of this sum-total is taken up by the naked-eye 

 appearances of cultures on various nutrient substrata ; in other 



