SOME OBSERVATIONS ON THE BACTERIAL CONTENT OF WATER IN WATERCRESS BEDS

SUMMARY: Samples of water flowing into watercress beds had higher bacterial contents during the summer months although this was less marked among samples from deep underground sources. Outlet samples showed higher contents than inlet samples and the bacterial content varied markedly with season, being highest in summer.
The presumptive coli-aerogenes contents at 30°, 37° and 44° also showed a similar seasonal variation among samples from the outlets but the marked inferiority of samples other than from bores was no longer apparent after the water had flowed through the beds. The dominant types were Bact. aerogenes type I, pectate liquefiers, Bact. coli type I, and Intermediate type I.
The importance of the pectate liquefiers was confirmed by plating on pectate gel and by their isolation from these plates and from MacConkey's broth.