128 SPONTANEOUS GENERATION. 



electric beam to be entirely pure and moteless. Other tubes containing 

 a like infused material, prepared under precisely similar conditions, were 

 placed in the ordinary air immediately adjacent to but outside the last- 

 named chambers, and the result awaited. It was this : In the course 

 of three or four days the tubes outside the chamber became turbid and 

 swarming with Bacteria and other organisms, while those in the inside were 

 as clear and sterile as on the day of preparation, and furthermore remained 

 in the same sterile and pellucid state for several months. At the end 

 of this period a door in the chamber wall was opened, so as to allow the 

 ingress of the ordinary atmosphere, and within three days after such 

 exposure they too became affected and swarming with bacterial life. One 

 logical inference only was to be derived from these results. The Bacteria 

 and other microscopic forms were abundantly present in their germinal 

 state in that ordinary and dust-laden atmosphere on the outside of the 

 closed chamber, and indicated their presence by falling into and freely 

 developing in the suitable nidus provided for them in the exposed tubes. 

 In the still, optically pure, and what may be correctly termed "empty," 

 atmosphere of the closed chambers they were, on the other hand, entirely 

 absent, though all the while, as the sequel demonstrated, beating against 

 the outside of the door and ready to rush in by millions to carry out their 

 work of infection and destruction immediately the portal was thrown open. 

 Varying his experiments in every conceivable form, a like ultimate result 

 was arrived at. Thus, since leading heterogenists had declared that a high 

 temperature was most suited for the production of de novo generation, and 

 especially one approximating that of 115° Fahr., tubes, with infusions as 

 before mentioned, were maintained at this temperature in one of the com- 

 partments of the Turkish Baths, Jermyn Street, for nine days without any 

 trace of life appearing. To meet, again, the argument that certain organic 

 infusions were more productive than others of spontaneously generated life, 

 well-nigh the entire catalogue of animal and vegetable substances used in 

 domestic economy, and including among the former beef, mutton, hare, 

 rabbit, kidney, liver, fowl, pheasant, grouse, haddock, sole, salmon, cod, 

 turbot, mullet, herring, whiting, eel, and oyster ; and among the latter 

 hay, turnips, potatoes, oatmeal, tea, coffee, hops, &c., were ransacked and 

 severally experimented upon by Professor Tyndall, but with the same 

 result. So long as the infusions were kept in pure and moteless air, so 

 long did they remain pellucid and free from the slightest trace of bacterial 

 or other life, but in all cases on exposure to the ordinary dusty and germ- 

 laden atmosphere, they became, within three or four days at the outside, 

 swarming with organic forms. A small pinch of dust from the laboratory 

 floor, or a dip on a needle's-point from a previously infected infusion, was 

 in either case found sufficient to inoculate the sterile tubes confined in the 

 moteless chamber, though the time occupied in the development of the 

 moving organisms in these two respective cases presented conspicuous 

 points of divergence. Where the inoculation was produced through a 



