170 ANIMALS AND PLANTS. 



of which certainly cannot be discriminated and brought 

 to their proper allegiance in any other way. 



Some months ago, Professor Tyndall asked me to 

 examine a drop of infusion of hay, placed under an ex- 

 cellent and powerful microscope, and to tell him what 

 I thought some organisms visible in it were. I looked 

 and observed, in the first place, multitudes of Bacteria 

 moving about with their ordinary intermittent spasmodic 

 wriggles. As to the vegetable nature of these there is 

 now no doubt. Not only does the close resemblance of 

 the Bacteria to unquestionable plants, such as the Os- 

 cillatorice, and lower forms of Fungi, justify this con- 

 clusion, but the manufacturing test settles the question 

 at once. It is only needful to add a minute drop of 

 fluid containing Bacteria, to water in which tartrate, 

 phosphate, and sulphate of ammonia are dissolved ; and, 

 in a very short space of time, the clear fluid becomes 

 milky by reason of their prodigious multiplication, 

 which, of course, implies tha manufacture of living 

 Bacterium-stuff out of these merely saline matters. 



But other active organisms, very much larger than 

 the Bacteria, attaining in fact the comparatively gigantic 

 dimensions of -J^TF of an inch or more, incessantly crossed 

 the field of view. Each of these had a body shaped like 

 a pear, the small end being slightly incurved and pro- 

 duced into a long curved filament, or cilium, of extreme 

 tenuity. Behind this, from the concave side of the in- 

 curvation, proceeded another long cilium, so delicate as 

 to be discernible only by the use of the highest powers 



