24 ART. 10. — S. KüSAKABE. 



The only closing remark that can be properly added is that 

 the result of these experiments as a whole has only brought the 

 author, who at first sight thought he had found a quarry of 

 research that would soon be exhausted, to the threshold of a 

 labyrinth, where many paths invites him to proceed further. 



In conclusion, I wish to express my great indebtedness to 

 Dr. N. FuKUCHi of the Geological Laboratory, for valuable in- 

 formation concerning the geological characters of the specimens. 

 My best thanks are due to Professor H. Nagaoka, under whose 

 kind guidance I have carried out the experiments. 

 June 190Ô. 



Physical Laboratory, College of Science, 



Tokyo Imperial University. 



