GERMS IN THE AIR. 



was present, or in some other kind of organic matter 

 which has dried up. Thus some of the germs 

 become protected in the same manner as the living 

 germs of vaccinia and of variola are preserved in the 

 partially dried lymph. In this way, as is well known, 

 they will retain their vitality even for many weeks 

 upon the point of a lancet or upon a glass or ivory 

 plate. 



On Detecting Disease Germs in the A ir. Various 

 methods for detecting germs in the air have already 

 been referred to when the subject of vegetable germs 

 was under consideration. It remains now only to 

 describe the apparatus recently devised by Dr. Mad- 

 dox, for collecting from the atmosphere all foreign 

 particles suspended in it. A full account of the 

 instrument in question is given in the " Monthly 

 Microscopical Journal" for June 1st, 1870, p. 286. 

 The arrangement will be understood, if the figures in 

 Plate XX, copied from those illustrating Dr. Mad- 

 dox's paper, be referred to. 



In Fig. 74, the instrument is so placed as to be 

 used like a vane outside the house. By slipping off the 

 vane, and placing the rest of the apparatus in a 

 vertical instead of horizontal position, and attaching 

 to it another short tube (Fig. 78) with a metal pipe 

 terminating in a small funnel, it can be used over a 

 cesspool, in any nook or corner, in an ordinary room, 

 in a cow-shed or stable, or in a ward near a patient 

 suffering from any infectious disease. A draught of 



