.] Examples of 'Saprophytes. Nomenclature. 73 



we cannot attempt to give an account of all the phenomena 

 which have been described. We confine ourselves to such as 

 are at present best known, and are at the same time of more 

 general interest. It is to be presumed that many more will 

 have to be added to these in the course of time, and that various 

 changes will have to be made in the views at present enter- 

 tained. We are still very much in the position of beginners as 

 regards our knowledge of these matters and our investigations. 

 Secondly, we do not propose to go any further into the details 

 of the chemical processes attending the work of decomposition ; 

 we are chiefly concerned with the morphological and biological 

 points of view. Thirdly, we must keep clearly in mind that our 

 knowledge of the morphology and biology of the Bacteria is at 

 present very imperfect, or at least very unequally developed. 

 So much is this the case, that we are not yet in a position to 

 attempt a consistent classification and nomenclature on the 

 principles of systematic botany. What at present seems like 

 such a classification is only a temporary expedient. In such a 

 case the only thing to be done is to agree upon a provisional 

 arrangement and nomenclature for the time being. We will 

 therefore, first of all, adhere to the primary division into endo- 

 sporous and non-endosporous or arthrosporous forms proposed 

 in Lecture III. Single better-known groups in these two 

 divisions may and must then be constituted genera, and receive 

 names capable of being precisely defined. We limit the use of 

 the name Bacillus, and apply it to all endosporous forms and 

 species with rod-like vegetative cells and cell-unions of the 

 first order. Single arthrosporous forms, such as Beggiatoa, 

 Cladothrix, Leuconostoc, Sarcina and others, may be separated 

 from the rest and distinguished by characters which will be de- 

 scribed presently. There still remain a number of forms, in 

 respect of which we are reduced to superficial distinctions of 

 shape, and their ultimate classification must therefore be deferred. 

 Among these the spiral forms may be included under the name 

 Spirillum. Some of these, according to van Tieghem, belong 



