ir)2 Decoinpoiiitioii oj' Ctfhifosc 



tilaiiu'utoiis form piodoiuiiiatos in tlio early stages of urowth. and the 

 splioriial form occurs more abundantly in older cultures, it is c|uite 

 unjustifiable to dediu'c from this that the "siioroid" constitutes a 

 restinsi staue or that it is in an\' deuree iihysioloiiically less active than 

 the earlier form. 



Aerobisw. S. cytophaga is essentially aerobic in chai-acter, and 

 practically the only decomposition of (•ellulose occurs at or sliuhtly 

 above the level of the culture solution. In those cases whore the cellulose 

 sinks to the bottom of a comparatively shallow layer of lii|uid as, fur 

 instance, occurs with culture solution ccmtaininu |>recipitated celhdose, 

 "rowth proceeds with extreme slowness. 



Developmental ci/cle of S. cytophaga. The construction of the 

 developmental cycle of (S. cytophaga is associated with ditticulties which 

 up to the present we have not been able entirely to overcome. In the 

 first place, the most satisfactory method of ]n'ocedure is admittedly the 

 adoption of the han^in^-drop culture method in which continnous 

 observations of the development of any specitic oruanism may he made. 

 Unfortunately, and in spite of a considerable amount of work with a larije 

 ininiber o( media, we are still without a synthetic mediun\ on which the 

 organisms can be well isolated and which permits of growth observa- 

 tions. The use of cellulose, either as fibre or in the form of a precipitate, 

 is obviously unsuitalile on account of physical interference with the 

 image of the organism. From time to tin\e attempts have been made 

 to employ the Indian ink method, but without any degree of success. 

 On the other hand the diminutive size not so much of the cell itself but 

 of the cell structures- which apparently undergo a series of changes — 

 renders it difficult even with the use of the highest magnifications to 

 obtain any definite idea of the exact sequence of the changes which 

 proceed in active cultures. 



Under these circumstances the cycle of development outlined below 

 is only submitted tentatively and is therefore subject to such revision 

 as future experience nuiy indicate. As far as possible photomicrographs 

 have been secured of typical intermediate stages between the threail 

 and the spmoid forms and some of these are given mi Plates 1 111. It 

 ma\' also be added that in those instances where a particular cell exhibits 

 noteworthy features, the photographs are so arranged that such cells 

 are below the centre and in line with the vertical axis of the plate. 



Two types of growth of »S. cytophaga appear to be distinguishable. 

 The first may be termed the direct, or purely vegetative, growth whereby 

 new cells are formed by transverse tission, and which proceeds extensively 



