202 THE SEVEN FOLLIES OF SCIENCE 



well-known toy called the artificial fish will flop its tail 

 when after being well dried it is laid on the moist hand. 

 In these cases we know that there is no animal life either 

 in the shaving or in the fish, and the cause of the phe- 

 nomenon is obvious and easily explained; but in the case 

 of the hair, associated as it is with a real living worm of 

 almost identical appearance, the ordinary mind is more 

 easily deceived. The general impression amongst those 

 who have not made a special study of the subject is that 

 voluntary movement on the part of any organism implies 

 the presence of animal life, and for a long time several 

 microscopic plants which are now known to be true vege- 

 tables, were believed to be animals because they were 

 seen to move about in the still water in which they floated. 

 This was the case with many diatoms and desmids, and 

 the beautiful volvox globator, which is unquestionably a 

 vegetable, was long known as the "globe animalcule" 

 and was believed to be an animal because it seemed to 

 have the power of voluntary motion. Few sights are 

 more strikingly beautiful than the appearance of a well- 

 developed volvox passing across the field of view of a 

 microscope with a steady rolling motion, thus giving one 

 the impression of a large green globe obeying the instincts 

 of animal life. 



This free motion from place to place was of course seen 

 to be very different from the movement of the sensitive 

 plant or the movement of flowers under the action of the 

 sun, and it was thought that it could only be attributed to 

 animal life. 



Of course in the present state of biological knowledge it 

 would be futile to offer any arguments against this old 

 belief. The microscope gives us ample assurance that it is 



