CH. X. MORPHOLOGY OF THE BACTERIA, ARTHROSPOROUS BACTERIA. 475 



simply Nostocaceae or Schizophyta which contain no chlorophyll ; at the same time 

 the position of the entire group in the general system remains still undetermined 1 . 



Of the forms which are here termed Endosporous Bacteria it can only be said at 

 present that they come nearest of all known forms to the Arthrosporous Bacteria, and 

 apparently are very nearly allied to them. It may be repeated in this place that the 

 sharp separation between the two groups rests on the knowledge of them which we at 

 present possess, and may disappear with its extension. Till then the separation must 

 be maintained, and it must remain an open question whether the resemblance between 

 the two groups really implies close affinity, or whether the endosporous forms may not 

 stand in still nearer relationship to other members of the system. If we look around 

 us under the guidance of ascertained facts for such affinities, we are led once more, 

 as Butschli has also pointed out 2 , to the Flagellatae. The arthrosporous form 

 such as Beggiatoa, with their generations alternating between a state of rest and one 

 of swarming movement by aid of cilia, show an unmistakeable resemblance to the 

 simpler forms of that varied group. The mode of forming their spores which is 

 characteristic of the Endosporous Bacteria finds its analogue, as far as we can 

 venture to speak in the present state of our knowledge, only in the formation of the 

 spores or cysts, to use the customary phrase, in the simple Flagellatae s known as 

 Spumella vulgaris, Cienk., and Chromulina. In these species the spore is formed, 

 as in the Bacteria in question, inside and from a portion of the protoplasm of a 

 cell, and this mode of formation occurs nowhere else among the lower Thallophytes. 

 We may at least suspect that a homology is indicated by this in itself only analogous 

 phenomenon, but the facts which have been observed lend no support to the 

 assumption. In dealing with this question we must keep well in mind that we are 

 not equally well acquainted with all portions of the range of organisms included 

 under the name Flagellatae, especially as regards the course of development of the 

 species, and that their affinities must be to some extent obscure and uncertain. For 

 this reason we will not add anything further to the remarks which have now been 

 made. 



But if we assume for a moment a connection between the Bacteria and the 

 Flagellatae, it is evident that as a consequence the following series of forms converge 

 to the Flagellatae : firstly, the series of Bacteria and Nostocaceae ; secondly, that 

 of the Mycetozoa (see page 445) ; thirdly, that of the chlorophyllaceous Algae, 

 with which are connected in ascending line the main series of the vegetable kingdom 

 and of the Fungi as one or more lateral branches *, and perhaps also side by side 

 with the chlorophyllaceous Algae some smaller groups which are now placed with 

 the Chytrideae ; fourthly and lastly the Rhizopoda and the Protozoa with the 

 Animal Kingdom which connects with these in an ascending line. On the above 

 assumption the position of the series of Bacteria in the whole system would be the 

 definite one of a group of organisms linking with the Flagellatae as a common 

 point of commencement and departure, and coordinating with the series of the Algae 



1 Bot. Ztg. 1881, i. 2 Biitschli (as cited on page 453), p. 808. 



3 Cienkowski in Schulze's Archiv f. mikr. Anat. VII, p. 434. BUtschli, (as cited on page 453), 

 pp. 797, 8i6,t. 45. 



4 Bot. Ztg. 1 88 1. 



