MONSTROSITIES 277 



Mr. Hutchinson evidently did not feel satisfied that the usual 

 small variations have been always sufficient to account for certain 

 structural} phenomena which would seem to leave unexplained 

 gaps behind them in the course of development. For after stating 

 that surroundings must have had a great deal to do with the 

 changes wrought on the structure of animals, he says : ^ ' There is, 

 however, another cause which may be of even greater importance, 

 although it cannot be so easily understood — and that is internal 

 changes in the animal itself. All the creatures we see around us 

 are constantly varying, and have done so in the past — now in one 

 direction, now in another. The cause of " variation " is one of the 

 unsolved problems of modern biology or the study of life ; but we 

 do know that a variation occasionally happens to be of such a 

 kind as to make a radical change in the organism, and to fit it 

 for new conditions of life better than its comrades of the same 

 species.' As an example of such a change he quotes the power of 

 ' gestation,' ' whether acquired at once, by some individual, or only 

 slowly brought about after many generations.' 



Zoologists have invented the terms ' aberrant forms ' to denote 

 forms of animals which do not conform to the theory of ' gradual 

 accumulation of small variations.' 



Among fishes there are numerous forms which might have 

 originated in a sudden ' aberration.' For instance, there are two 

 forms of Sword-fish, the ordinary one {Histophorus), with its 

 upper jaw prolonged into a sword-like point ; and various species 

 of Hemiramphiiis? These have the lower jaw prolonged in a sword- 

 like point. Both these forms may have originated suddenly in 

 fishes with equal jaws, either by a monstrous enlargement of one 

 jaw, if both jaws were small, or by a monstrous dwarfing of one 



1 Creatures of Other Days, p. 178. 



^ Fishes of India, by Francis Day, part iii. pi. cxix. 



