as the Fundamental Form of Movement. 157 



tional as3nnmetry in the animal. It must here, however, be 

 stated distinctly that this circular movement is not to be 

 confused with the manege-movement known in physiology in 

 the case of brain-lesion ; for a series of morphological inves- 

 tigations undertaken by Prof. G. A. Guldberg renders it in 

 the highest degree probable that the actual cause of this 

 " senseless " circular movement is to be sought in the asym- 

 metrical structure of the organs of locomotion, as to which a 

 short communication will be found in the next number of this 

 periodical (Biol. Centralbl.). 



This circular movement also appears in the life of animals 

 in the natural state so soon as the impressions derived from 

 the senses are unable to exercise a guiding influence. 



For a series of movements in circles which, so far as they 

 were known, stood out as inexplicable riddles, must be 

 regarded as results of the physiological action of circular 

 motion upon natural motion guided by imperfect cerebral 

 activity and failing senses. The forms of movement thereby 

 produced, which become more or less regular circles, and are 

 in part well-known phenomena in the case of higher animals 

 and human beings, I have termed provisionally biological 

 circles or circular wanderings. 



In spite of the fact that in this connexion there is reason 

 to suppose that similar phenomena in the life of insects can 

 or must be explained in the same way as in Vertebrates, 

 owing to the want of physiological experiments I can do 

 nothing more here than merely to allude to this circum- 

 stance. In the case of higher animals, especially birds and 

 mammals, on the contrary, the phenomena that have been 

 observed are so numerous and the physiological experiments 

 so far advanced that I now consider myself justified in pro- 

 pounding the theory as to the reality and signification of 

 circular motion. 



By questioning divers, who nowadays use electric lamps at 

 the bottom of the sea, and lighthouse-keepers on the coast of 

 Norway, I have obtained statements to the eflfect that in the 

 places where these men work a variety of phenomena are 

 always observed that are traceable in the same way — namely, 

 circles described by fishes swimming in the light of the 

 electric lamps and similar circular flights on the part of birds 

 in front of the lighthouse (not round it). The easiest and 

 most natural explanation that can be given of these move- 

 ments is that they are " biological circles," which arise from 

 the fact that the animal is blinded by the light, from which 

 it seeks to get away by swimming or using its wings ; since, 

 however, it cannot find anything else to show it the way, 



Ann. dc Mag. N. Hist. Ser. 6. Vol. xix. 12 



