4 
(1-2 per cell) which are capable of surviving under conditions that the 
mother cells cannot. The capability of these minicells to disseminate 
genetic information to other cells was not extensively tested, nor was a 
detailed study of the survival of this capability performed. Minicells 
are known to act as genetic donors, as well as recipients, during 
conjugational processes (Frazer and Curtiss, 1975) (see this paper, 
§ §Allc , B25) . 
Fifth, the strain survives better in minimal environments* than in 
rich ones lacking the growth factors required for viability*. This 
would allow for dissemination in famine environments, such as drains, 
without appreciable death, and rapid exchange of genetic information in 
suddenly richer environments, such as sewers (see this paper, §§A8a, A12a, 
A12b , A13 , B22, B26). 
Sixth, the introduction of the pSClOl plasmid vector into' Xl?76 
allows it to survive much longer under certain conditions than Xl?76 
alone.. This is the first evidence obtained on the effects of introducing 
additional DNA into Xl?76 upon its survival. The result is that intro- 
duction of this particular additional DNA into Xl?76 increases its 
possibilities for survival. It should be noted that in none of the cases 
tested, does yl876 survive less well than under the identical 
sets of conditions (see this paper, §§A10c, A12a, A12b, A13, AlAc, A18, 
A19, A20) . 
* By "minimal environments" we denote either BSG (buffered saline with 
gelatin), tap water, or distilled water. 
By "rich ( cnyironments ] lacking the growth factors required for viability" 
we denote that class of media lacking either thyinid ine/thymine or DAP, 
such as L broth + thymidine, Ml. + casanino acids + thymidine, biotin, 
[Appendix C — 192] 
