52 



may be favoured and hastened by selection, it would take place without selection, 

 while selection could not produce adaptations without the inheritance of acquired 

 characters. They maintain, in fact, that there is no evidence of the occurrence of 

 such variations as would give rise to adaptations except under the influence of 

 stimuli and functional exercise. 



Thus these evolutionists would explain the distortion of the eyes in flat fishes in 

 this way. A species of fish took to crouching flat on the ground on one side of the 

 body. But at first they did not lie perfectly flat, but slanting, lifting up their heads 

 so as to use the lower eye, and using the muscles of this eye so as to turn the pupil 

 into a horizontal direction, and look along the edge of the head. In consequence of 

 this, the lower eye pressed on the interorbital septum, and caused it to be flattened. 

 This pressure being continued for millions of generations the flattening and distortion 

 of the interorbital septum came to be inherited until at last the two eyes were on one 

 side of the head. 



Now it is clear that no action of a given muscle of the eye could transport 

 that muscle from one part of the head to another, and evolutionists who had not 

 studied the anatomy of the head of flat fishes have made that objection to the above 

 explanation. But no such transjjortation has occurred as was shown in the description 

 given above. The attachment of the recti muscles of both eyes remains in the flat 

 fish exactl}' where it is in the symmetrical fish. The cranial region aiid branchial 

 rcjjion are unaltered. But the fishes which were the ancestors of the existing flat 

 fishes, in order to twist the lower eye till its optical axis was almost parallel to the 

 surface of the head, must have used the oblique muscles belonging to that eye. It is 

 a physiological necessity that such a constant and extreme exertion of those muscles 

 must in the individual have produced structural modifications, especially if it was 

 commenced at an early age. The eye must have pressed on the interorbital septum 

 in the sole oti the left side, and this pressure would not have been counteracted by 

 any pressure on the other side, for the right eye was required to look upwards and 

 ventrally. Such pressure must have caused absorption and distortion of the inter- 

 orbital septum, that is to say, the septum would by that alone have become thin and 

 flat and bent to the right side. The increased exercise of the left oblique muscles 

 must also have caused them to become larger and stronger, and also have resulted in 

 the enlargement of the bone to which they were attached ; for it is an established and 

 certain fact that the exercise of a muscle causes it to increase in size and causes an 

 increased development of bone at its attachment. But the direction of the strain of 

 the muscles must have caused a torsion of the bone to which they were attached, 

 so that the surface of attachment which originally looked outwards to the left came 

 to look upwards. These are exactly the changes which we find to have taken place 

 in the head of the sole. If the change had been due to the selection of variations 

 which were independent of the eflects of function, then we should expect that the 

 left ectethmoid would have remained symmetrical with the right, for the left eye could 



