276 THE AMERICAN MONTHLY [Oct 



But still they were alive, they possessed vitality, and this 

 was the manner vital things were known. They possess- 

 ed motion which was amoeboid. We can have things 

 which have amoeboid motion but which cannot by any 

 means be considered as living. They are dead matter 

 and have never been alive. 



Professor Bernstein explains, in a recent number of Archiv 

 fur die gesammite Physiologie, an application in which he 

 imparted to a drop of metallic mercury the faculty of real 

 locomotion. One of the most successful forms of his ex- 

 periment was this: He put a drop of mercury into a suit- 

 able dish of which the bottom was perfectly level ; then 

 he poured in a sufficient quantity of dilute nitric acid and 

 laid a little piece of potassium bichromate at a distance 

 of several centimetres from the drop of mercury on the 

 bottom of the dish. The yellow solution of the crystal be- 

 gan to spread itself in a circle, and as soon as it reached 

 the drop of mercury, the latter with a brief tremor be- 

 gan to move and then dashed straight to the crystal which 

 it reached in a few seconds; and then, in the liveliest man- 

 ner, repeated the twitching movements already described. 

 If, in consequence, the crystal moved away in any direc- 

 tion, the drop pursued it, receded and approached, again 

 and again, with a mingled leap and glide while stretch- 

 ing forth long tentacles and quickly drawing them back 

 again. This lively play leads an observer to think that 

 the movements are those of a living organism. They last 

 until the crystal is consumed or the drop has accidentally 

 moved too far away from it. These remarkable phenome- 

 na may be considered as adequate support of the view 

 held by the botanist Barthold, the physicist Quincke, and 

 the physiologist Verworn, that the amoeboid and related 

 movements are the result of changes in the tension of 

 the surface of the living substance. Obviously, though, 

 there are still other conditions which can vary largely 

 the movements of the living prototype. It has been known 



