GERM-THEORY OF DISEASE. 349 



majority of the spores of Schizophytes which are also found. Michel 

 has calculated that in the neighbourhood of the observatory at 

 Montsouris a man may inspire in 24 hours 300,000 mould spores 

 and 2,500 Schizophytes. Probably not ^th of these are possessed 

 of any life or capacity for further development, but Michel has 

 nevertheless discovered that the curve representing the occurrence 

 of Schizophytes in the atmosphere, and the curve representing the 

 prevalence of infectious diseases, are coincident. He has shown the 

 necessity for ventilation by pointing out the great increase of 

 microbes in the atmosphere of the Parisian hospitals during winter, 

 when doors and windows are kept close for warmth's sake. He nas 

 also shown that microbes are not more abundant in the neighbourhood 

 of open sewers than in the air generally, a fact which is confirmed by 

 investigations of Hansen and Xaegeli. The latter demonstrates that 

 all micro-organisms must be previously dried before being carried 

 into the atmosphere. They exist there generally in the spore- 

 condition, a condition which usually steps in when changes unfav- 

 ourable to the ordinary method of propagation by division have eome 

 into operation. The spores, which are produced in the interior of 

 the cells of the Schizophytes, are possessed of much greater vitality 

 than the mother-plants, being able to resist extremes of temperature, 

 and deprivation of moisture and food immeasurably better than 

 these. The discovery of such spores and their properties has given 

 a death-blow to the doctrine of spontaneous generation, for it is now 

 satisfactorily determined that any organic infusion may be kept per- 

 fectly free from micro-organisms in a sealed flask, if the proper 

 precautions have been taken not only to kill the mature Schizophyte 

 in it, but also their spores. 



It is not surprising in view of these facts that the strength of the 

 disinfectants used to kill septic material must be very different 

 according as the material is in a vegetating or spore-condition. In 

 the latter case no volatile antiseptics, except chlorine and bromine, 

 have been found to possess any efficacy, and it has been shown 

 that the antiseptic virtues of carbolic, salicylie, &c, have been 

 greatly overestimated. As a result of various experiments made to 

 determine the best means of disinfecting clothes (rags impregnated 

 with spores of Bacillus anthracis being chiefly employed), prolonged 

 boiling — for several hours — has been recognized as the simplest effi- 

 cacious method. The experiments have shown that the process of 



