662 CONTIUBUIIONS TO OUR KNOWLEDGE OF S01L-F"KRTlL,ITY,vi., 



garden soil, had been seeded into a bcan-iiii'usioii, and, ai'tei' a 

 time, a rich growth of aiiuebjc was found. The suspension was 

 centrifugalised, and the sediment rapidly washed with 0-2% saline. 

 The ani«3bje were suspended in saline, a part of which was heated 

 for 10 minutes at 62° to 64°. To each 20 grm. portion of soil, 

 4 c.c. of suspension were added. This contained, in the case of the 

 unheated suspension, (i.OSO living motile ama'ba?, no motile ciliates, 

 many cysts, presumably of the latter, and many bacteria. 



Experiment ii. — The Addition of Au(EBJ!:. 



The experiment was repeated and confirmed at a later date, with 

 a poor sandy soil. The tests were contained in small bottles closed 

 with wooden corks, through which ])assed glass tubes furnished 

 with open capillary ends of approximately 1 mm. bore. The 

 evaiDoration from the soil was very small, the loss being equal to 

 only 037% in 73 days at 22°. Each test received four c.c. of a sus- 

 pension of Amoeba Umax in 0-2% saline. This quantity contained 

 2,720 moving and 800 encysted amcebee, together with a mixed 



pairs of bacteria cease their motion as the protozoal arm touches them, but 

 in a few seconds they are as active as ever. I have seen an amajba, in 

 moving forwards, touch a rod-shaped microbe which adhered to the 

 surface, sliding over but still maintaining its position in the tield, until 

 tlie terminal was reached. There it remained attached. Meanwhile, 

 another microbe was similarly treated, but somehow became detaclied 

 from the terminal. In its circumambient wandering, the anuuba touched 

 the same bacterium, and both became fixed to the terminal tuft of barely 

 visible slime, until a fragment of debris, encountered by the protozoon, 

 proved too weighty, and fragment and bacteria were left behind. Mouton 

 [Ann. de I'lnst. Past., xvi., p. 476] seems to have seen, in this entangle- 

 ment, an agglutination of the microbes by an agglutinin secreted by tiie 

 pulsating vacuole. 



