De Zouche. — Bacteria and their Belation to Disease. 39 



another place (1860), " What would be most desu'able would 

 be to conduct these studies far enough to prepare the way for 

 a serious investigation as to the origin of various diseases." 

 M. Pasteur's experiments and words such as I have just 

 quoted set Davaine thinking about the connection between 

 the rods seen by Eayer in anthrax and the causation of that 

 disease, and had for immediate effect the experiments in 

 antiseptic surgery by Lister, which have been followed by 

 such brilliant results. We are thus brought back to the views 

 of Hippocrates and his successors as to the Tn'evfxa or spiritus in 

 the air with which we inhale the origin of disease as well as 

 the principle of life. We have here, too, the explanation of 

 what Sydenham, in the seventeenth century, termed the 

 " latent and inexplicable alteration of the air infecting the 

 bodies of men." 



The views of Bastian may be given as those of one of the 

 most recent supporters of the doctrine of heterogenesis. In 

 a solution containing organic matter he describes the aggre- 

 gation of minute portions of protoplasm — the plastide particles 

 — in a film — the proligerous pellicle ; and he maintains that 

 " bacteria are produced as constantly in a solution of colloidal 

 matter as crystals are produced in a solution containing crys- 

 tallizable matter." He says, in his conclusions, " Both obser- 

 vation and experiment unmistakably testify to the fact that 

 ' living ' matter is constantly being formed de novo in obe- 

 dience to the same laws and tendencies as those which deter- 

 mine all the most simple chemical combinations, the qualities 

 which we summarise under the word ' life ' being in all cases 

 due to the combined molecular actions and properties of the 

 aggregate which displays them, just as the properties which 

 we include under the word ' magnetism ' are due to particular 

 modes of collocation which have been assumed by the mole- 

 cules of iron." Bastian, however, neglected to sterilise his 

 jflasks by passing them through the flame, and the omission 

 was sufficient to discredit his conclusions with the scientific 

 world. The balance of scientific opinion at the present day is 

 very largely in favour of biogenesis as applied to the origin of 

 bacteria, as well as to all forms of life ; indeed, the doctrine of 

 omnis cellulcd cellula is all but universally accepted. Davies 

 (quoted by Hirsch) says, "I would as soon believe in the 

 spontaneous generation of human beings as I would in the 

 spontaneous generation of typhus." 



The real discoverer of bacteria was Leeuwenhoeck, of 

 Delft, born A.D. 1632. Without entering into any detailed 

 description of bacteria, which may be found in any of the 

 systematic works on the subject, it will be necessary to give 

 an outline of their general characteristics in order to the better 

 understanding of the manner in which they settle and multiply 



