Protozoa in Relation to Soil Bacteria. 307 



abcait 100 per gramme, would no doubt multiply alongside the added protozoa, 

 having a suitable medium in which to grow, and thus contribute towards the 

 more speedy attainment of the 30,000 in this soil than in the other, where all 

 the protozoa were eradicated. 



3, Mass Inoculations of Protozoa. 

 Turning now to a consideration of the curves for the other soils. Toluened 

 ■plus ciliates in hay-infusion (T + C), Toluened plus mixed culture of protozoa 

 and bacteria in hay -infusion (T-fM), and Toluened plus hay-infusion 

 filtered through a Berkfeld filter (T + F), which are represented in fig. 4 



Days 



Fig. 4. 



along with the curves of Toluened plus sterile distilled water (T + W) and 

 the untreated (U), we notice a marked difference from the curves already 

 discussed. 



The (T + C) and (T + M) each show a remarkably high bacterial content 

 at 21 days, followed by an equally sharp drop at 43 and 78 days, after which 

 the fall in numbers is more gradual. Only at 190 days do they reach a 



VOL. lxxxix. — B. 2 c 



