PROFESSOR TYNDALUS RECENT RESEARCHES. 697 



the 12tli all the tubes had given way ; but the diiferences in their 

 contents were extraordinary. All of them contained bacteria, some 

 few, others in swarms. In some tubes they were slow and sickly in 

 their motions, in some apparently dead, while in others they darted 

 about with rampant vigor. These differences are to be referred to 

 differences in the germinal matter, for the same infusion was present- 

 ed everywhere to the air. Here also we have a picture of what oc- 

 curs during an epidemic, the difference in number and energy of the 

 bacterial swarms resembling the varying intensity of the disease. It 

 becomes obvious from these experiments that of two individuals of 

 the same population, exposed to a contagious atmosphere, the one 

 may be severely, the other lightly attacked, though the two individ- 

 uals may be as identical, as regards susceptibility, as two samples of 

 one and the same mutton-infusion. 



The author traces still further the parallelism of these actions with 

 the progress of infectious disease. The Times of January iVth con- 

 tained a remarkable letter on typhoid fever, signed "M. D.," in which 

 occurs the following statement : " In one part of it (Edinburgh), con- 

 gregated together and inhabited by the lowest of the population, 

 there are, according to the corporation return for 1874, no less than 

 14,319 houses or dwellings many under one roof, on the ' flat ' sys- 

 tem in which there are no house-connections whatever with the street- 

 sewers, and, consequently, no water-closets. To this day, therefore, 

 all the excrementitious and other refuse of the inhabitants is collected 

 in pails or pans, and remains in their midst, generally in a partitioned- 

 off corner of the living-room, until the next day, when it is taken down 

 to the streets and emptied into corporation-carts. Drunken and 

 vicious though the population be, herded together like sheep, and with 

 the filth collected and kept for twenty-four hours in their very midst^ 

 it is a remarkable fact that typhoid fever and diphtheria are simj^ly 

 unknown in these wretched hovels." 



This case has its analogue in the following experiment, which is 

 representative of a class: On November 30th, a quantity of animal 

 refuse, embracing beef, fish, rabbit, hare, was placed in two large 

 test-tubes opening into a protecting chamber containing six tubes. On 

 December 13th, when the refuse was in a state of noisome putrefac- 

 tion, infusions of whiting, turnip, beef, and mutton, were placed in the 

 other four tubes. They were boiled and abandoned to the action of 

 the foul "sewer-gas" emitted by their two piitrid companions. On 

 Christmas-day, these infusions were limpid. The end of the pipette 

 was then dipped into one of the putrid tubes, and a quantity of matter, 

 comparable in smallness to the pock-lymph held on the point of a 

 lancet, was transferred to the turnip. Its clearness was not sensibly 

 aftected at the time ; but, on the 26th, it was turbid throughout. On 

 the 27th, a speck from the infected turnip was transferred to the 

 whiting; on the 28th, disease had taken entire possession of the 



