$ v.] Origin and distribution. 37 



Hence the Bacteria have been arranged in one group with 

 the Nostocaceae, and this group has received the name of 

 Fission-plants or Schizophytes ; the Nostocaceae which contain 

 chlorophyll are Fission-algae, those which have no chlorophyll 

 are Fission-fungi. 



The entire group of the Schizophytes is somewhat isolated in 

 the general system ; a closer association with other groups can- 

 not be established at present, and it would lead us too far away 

 from our more immediate subject to enter further into the con- 

 jectures which may be formed about them. So much however 

 is beyond doubt, that most Schizophytes, the Nostocaceae 

 especially, have all the characteristics of simple plants. They 

 show a very slight approximation to the Fungi, in the sense in 

 which that term is used in the natural system, as has been 

 already stated in the Introduction. We can only say therefore 

 that the Bacteria, together with the rest of the Schizophytes, are 

 a group of simple plants of a low order. 



The old observers regarded them as belonging to the animal 

 kingdom and to the group of Infusorial Animalcules, chiefly on 

 the ground of their motility and in the absence of the basis re- 

 quired for a more exact comparison. At present there is no 

 reason for separating them from the vegetable kingdom, though 

 it is merely a matter of convention in the case of these simple 

 organisms where and how we should draw the line between the 

 vegetable and animal kingdoms. 



V. 



Origin and distribution of Bacteria. 



WE commenced our survey of the mode of life of the Bacteria 

 by explaining in what manner and from whence they make their 

 way to the spots where we find them. 



If we adhere to the general result of the foregoing con- 

 siderations, namely, that Bacteria are like other vegetable growths, 



