REPRODUCTION OF BACTERIA 13 



that in a few species sister cells conjugate and from this 

 conjugation a spore arises. Hort l also claims that the 

 life-cycle of Bacteria is by no means a simple one, and 

 Lohnis and Smith 2 state that bacteria live alternately 

 in an organised and in an amorphous stage. In the 

 latter, the living matter of several cells unites and 

 undergoes a thorough mixing, a large mass or " symplasm " 

 being formed, from which small bodies, " regenerative 

 units and bodies," develop and ultimately become cells of 

 normal shape. Direct conjugation between two or more 

 cells was also observed. Small bodies or " gonidia " were 

 also found to be liberated from the bacterial cells, the 

 gonidia in some cases being so small as to be filterable 

 through a porcelain filter. The gonidia form either 

 regenerative bodies or occasionally exospores. 



Reproduction by transverse fission is common to all 

 bacteria ; the bacterial cell becomes constricted at its 

 middle and finally separates into two parts, and thus 

 two young cells take the place of the parent one ; repro- 

 duction by fission is therefore also an increase in numbers. 

 The fission is always transverse, never longitudinal, 3 the 

 rule being in cell-division that the new membrane is 

 formed in the most economical manner. Longitudinal 

 division, on the other hand, is comparatively common 

 among the Protozoa. Previous to division the rod-forms 

 become elongated and the spherical ones ellipsoidal, and 

 there is an increase in the number of the roseine-staining 

 granules, partly by division of pre-existing ones and partly 

 by new formation. The constriction in the majority of 

 cases involves and passes through one of the granules. 

 In the monotrichous and lophotrichous bacteria it is 



1 Brit. Med. Journ., 1917, vol. i, p. 571. 



2 Journ. Agricult. Research (Washington), vol. vi, 1916, No. 18. 



3 Longitudinal division has been described in a few species, but its occur- 

 rence is so rare that it seems doubtful if these forms be true bacteria. 



