Organisms Consisting of One Cell 259 



the bacterial membrane, two facts seem to indicate its active 

 charax'ter: the presence in many species of a mucous en- 

 velope, presumably secreted by the membrane, and the pres- 

 ence in many others of cilia which in some cases are almost 

 certainly outgrowths of the membrane. It seems to have 

 been proved that in Spirilluni gigantcani, the ciliary tuft 

 with which each end of the body is armed arises from the 

 inner body mass and passes through a chink in the mem- 

 brane. Meyer and a few other authorities consulted are of 

 the opinion that this is the typical mode of origin. But too 

 many capable observers are positive about their having 

 demonstrated the origin of the cilia from the membrane 

 in widely separated species to permit us to believe that 

 this is not in fact the mode of origin in many species. Thus 

 V. A. Moore : "The flagella appear as hair-like appendages 

 or filaments, which radiate from the bacteria. They are 

 given off from the cell wall of the germs of which they 

 appear to be continuations or projections." ^^ 



So meager is our knowledge of the individual activities 

 of these minute beings that the simplest trustworthy obser- 

 vations in this field are welcome, and the following from 

 ^loore's paper is worth quoting even though its bearing on 

 the membrane question is only indirect. Speaking of the 

 behavior of the organisms when the cilia of several indi- 

 viduals become entangled with one another the author says 

 they exhibit "a trembling motion, then a jerking, reeling 

 and pitching movement, until finally they are free and 

 move across the field," and "it seems highly probable that 

 detachment or breaking of the appendages is produced dur- 

 ing these voluntary movements, b^^ their contact and pos- 

 sible entanglement with each other." ^^ 



The probable active participation of the membrane in 

 the division of the bacterium is evidence from another di- 

 rection that the structure is a real part of the organization 

 of the being. 



