10 THE LOWEST FORMS 



unstable globule, in all its changes of form, was that it invari- 

 ably progressed with a certain part of its body forward ; and 

 upon close examination I found that this part had a peculiar 

 appearance which distinguished it from the rest of the body, 

 that is, it was covered with little knobs (a), and the interior was 

 perfectly clear and transparent, with not the least trace of mo- 

 tion to be discovered therein. This I shall call the head. This 

 was in marked contrast with what was to be seen in the other 

 part of the body, for there were the most unmistakable signs of 

 life, exhibited not only by the activity of the numerous particles 

 of food, but by the regularity with which they circulated in cur- 

 rents, having a fixed direction. The arrows which I have intro- 

 duced in the figures (A B) will indicate the trend of these 

 streams. Constantly and invariably the currents of food passed 

 backwards along the sides of the body to the posterior end, and 

 there uniting in a single stream, turned their course toward the 

 head, passing along the middle line of the body, and again 

 turned off right and left backwards along the sides. Nothing 

 could be more wonderful than this sight ; not a sign nor trace of 

 any interior organization which could be supposed to direct 

 these currents ; all was as clear as crystal, excepting the circu- 

 lating particles ; and they seemed as if impelled by magic. To 

 increase this almost unavoidable illusion, there was another 

 phenomenon which was connected with the movements of the 

 circulation, which I could not explain to myself for some time ; 

 I mean, that, with the exception of the head, the whole of the 

 body seemed to be gradually sliding on itself, and turning over, 

 end for end. This I knew could not be strictly true ; and yet 

 the deception to the optical senses was perfect, even after I had 

 discovered the cause of it. This is akin to what every one must 

 have observed whilst sitting in the cars at a station, when a 

 passing train gives to the one you are in the appearance of 

 moving ; and this cannot be banished from the impression until 

 the eye is cast upon some fixed object. The illusion in the case 

 of the Amreba was derived from the fact that the particles of 

 food, as they passed backward along the sides of the body, 



