no 



THE CYTOLOGY AND LIFE-HISTORY OF 



ACTERIA 



conjugations, with the nuclear material fused at the point of contact. Usually 

 only a single pair of bacteria will conjugate thus, but there seems little reason 

 to doubt that the star-hke clusters which have been reported in Phytomonas 

 tumejaciens and in cytophagas, as well as in many other genera, are exactly 

 similar, multiple conjugations. In the case of P//. tumefaciens the concentration 

 of Feulgen-positive material at the centre of the cluster has been described. 



Fig. 48 

 THE NUCLEAR REDUCTION PROCESS 

 (1) In Rhizobiuin ; a, b, c, d represent stages in the maturation of the resting nucleus, 

 and the ehmination of a small daughter nucleus. (Reproduced frn)ii Cold Spring Harbor 

 Symposia) . 



(2, 3) The elimination of the rejected daughter nucleus in Bacillus ; x, y shows two suc- 

 cessive stages in the same organism. Phase-contrast photographs in the living state. [Re- 

 produced from Experimenta .Cell Research, by permission of Prof. R. J . ]'. Pulvertaft). 



