PEE es IN le OE nr a aD Pe Pn eS ae 
1897 | OBSERVATIONS ON THE MYXOBACTERIACE.Z 399 
the Myxococcus group, for example, the species previously 
enumerated were all characterized by a practically sessile habit, 
and in the absence of a knowledge of their complete life history 
their close relationship to the more highly developed cysto- 
phore-producing forms might well have been questioned. The 
discovery, however, of the species subsequently described as 
Myxococcus stipitatus serves more definitely to indicate the close 
relationship between the two groups, since in this instance the 
Spore mass is raised above the substratum on a well developed 
stalk, corresponding exactly in structure and method of forma- 
tion to the often highly differentiated cystophores characteristic 
of nearly all the species of Chondromyces; the only difference 
being dependent on the fact that in the one case the ultimate 
mass or masses of individuals become encysted as such, while 
in the other they form an eventually deliquescent spore mass. 
A further indication of this relationship is also found in the 
characters which distinguish Myxococcus cruentus, the cysts in this 
species being very clearly differentiated, with a well defined wall ; 
Surrounding the mass of spores within, which are themselves 
embedded ina stringy, coherent though scanty matrix that recalls 
the corresponding condition found in the cysts of Chondromyces. 
The Spores, moreover, are not as well developed as in the other 
species of Myxococcus, and seem to suggest a transitional form 
between a slightly modified rod, such as occurs in the cysts of 
Chondromyces, and a typical spore like that which is found, for 
example, in Myxococcus rubescens. The general habit of the 
Species closely resembles that of Cystobacter as below emended ; 
and, were it not for the definite spores, might readily be included 
in that genus. In this connection it may be mentioned, more- 
Over, that an examination of the contents of mature cysts of 
Cystobacter fuscus shows that the rods in this case are more defi- 
‘Aitely modified than in the species of Chondromyces; their walls_ 
being visibly thicker and their contents enclosing the same 
definitely formed nucleus-like body described below as character- 
__ istic of the developing spores of Myxococcus. It should be 
_ Mentioned, however, that I have not yet had an opportunity of 
