6 5 4 T 7 ^ ^ 0P ULAR S CIENCE MONTHL Y. 



upon here. It was almost impossible to save a cucumber; I never 

 did succeed in saving a melon infusion from contamination, and from 

 this so-called spontaneous generation. But here, when the air had 

 been allowed to deposit all its motes, and when we were withdrawn 

 from an infected atmosphere, as I have said, the chambers were re- 

 turned with their infusions as clear as crystal. Mr. Cotterell will 

 show you some of them. You will see that one of these is muddy 

 and turbid, and it has a deposit at the bottom. These are all dead 

 bacteria, and the muddiness is due to swarming bacterial life. Here 

 you have two infusions perfectly clear. Why does the other tube give 

 way ? When we came to examine it, a little pinhole was found at 

 the bottom of the chamber, and through that pinhole the germs got 

 in. Here is a melon-infusion ; and, in order to show you what would 

 have occurred if the infusions had not been protected from the float- 

 ing dust of the atmosphere, we have hung beside this case two tubes 

 that have been exposed to the common air and have fallen into a state 

 of utter rottenness. In this way, from the Jodrell Laboratory at Kew, 

 we have had these cases returned with their infusions perfectly intact. 

 Even in our infected atmosphere, when we subject our infusions to 

 experimental conditions sufficiently stringent, we are able entirely to 

 shut out contamination, and to show that spontaneous generation 

 never occurs. When we get clear of our 'atmosphere altogether, 

 this is a matter of perfect ease ; and we find in Kew Gardens that 

 Nature runs her normal course. 



-+- 



RELATIONS OF THE AIE TO OUR CLOTHING. 1 



By Dr. MAX VO N PETTENKOFFEE, 



PROFESSOR OF HYGIENE AT THE UNIVERSITY OF MUNICH. 



THE committee of the Albert Society has honored me by an invi- 

 tation to give a few popular lectures at Dresden, on subjects of 

 public hygiene. Let me state to you at once what I think of popular 

 lectures in general. 



What ought they to be, and what can we expect from them ? I 

 am not one of those who, in all their work and aim, look out directly 

 for the practical use, for the return on the capital, immediate or pro- 

 spective ; but, on the other hand, I feel myself bound, in a certain 

 degree, to inquire into the object of much that may appear to be 

 cither unprofitable or useless. 



There is no doubt that popular lectures on scientific subjects will 

 not impart really competent knowledge, and will not form experts. 



1 Abridged and translated by Augustus Hess, M. D., member of the Royal College of 

 Physicians, London, etc. 



