698 REPORT— 1894. 



brief descriptions appended ; all claims to priority being dependent on the date of 

 this record. 



5. On the Relations of the Cranial Nerves to the Sensory Canal System 

 of Fishes. £yV^. E. Collinge. 



6. On some Models of the Crania of Siluroids. By H. B. Pollard. 



7. On the Epidermis of the Plantar Surface and the Question of Use- 

 Inheritance. By F. A. DiXEY, M.D., Fellow of Wadham College, Oxford. 



It is well Imown that in the human adult the skin of the sole of the foot is 

 thickened as compared -with that of the dorsum, and it is also known that this 

 local thickening on the plantar surface is present before birth. It is therefore not 

 the direct result of the use of the sole in walking, though it might possibly be held 

 to be due to use-inheritance. But in addition to the general plantar thickening, 

 there is also known to exist a special thickening, in the adult, of the skin covering 

 the heel and toe-ball, which is no doubt correlated with the heel-and-toe gait 

 specially characteristic of man. It was suggested by the late Professor Romanes 

 that it would be of importance to ascertain the time of appearance of this special 

 as distinct from the general plantar thickening, inasmuch as its appearance before 

 birth, should that be proved to occur, would seem to be more easily accounted for 

 on the principle of use-inheritance than on that of pure natural selection. The 

 general plantar thickening in the embryo might be held to be simply representative 

 of the condition in a prehuman ancestor ; not so, however, the special thickening of 

 the heel and toe-ball. Six embryos, whose ages varied from about the third to the 

 ninth month, were examined in concert with Professor Romanes. As the inner 

 limit of the coriuni is in most cases not exactly determinable, the epidermis alone 

 was measured, and the results were as follows: — (1) The general plantar thickening 

 had begun in the earliest embryo examined. (2) The special thickening of the 

 toe-ball had also begun at the same age. (3) The special thickening of the heel 

 was not discoverable in any one of the specimens, which ranged up to the time 

 just preceding birth. These results were unexpected, for it had been anticipated 

 that both the special thickenings would have been found in the embryo to be either 

 absent or present together, and at first sight it seemed as if no light were thrown 

 by the observed facts on the question at issue. On further consideration, however, 

 and after special study of the gait of the lower primates, it appeared to the author 

 that the thickened epidermis of the toe-ball in the embryo simply represented an 

 ancestral condition when the gait resembled that of most monkeys, who walk, as a 

 rule, with the heel raised from the ground, only using the whole length of the sole 

 when resting or squatting. The phenomenon would, therefore, seem to admit of a 

 far more easy explanation under the theory of natural selection pure and simple 

 than under that of use-inheritance. 



Department of Botany. 

 1. 071 Pachytheca. By G. Murray. 



2. On the Structure of Fossil Plants in its bearing on Modern Botanical 

 Questions. By Dr. D. H. Scott, F.R.S. 



3. A Thames Bacillus. By Professor Marshall Ward, F.R.S. 



4. On the Influence of Light on Diastase. By Professor J. R. Green. 

 5. A Contribution to the Geological History of Cycads. By A. C Seward, 



