ZOOLOGY. 369 



evidence of the truth of the theory. The same rumbling is sometimes observed 

 in yawning ; oftener, however, when the yawning organs act with the mouth 

 closed ; also, to a slight extent, in swallowing. By the action of these organs, 

 the curves of the avenues to the drum become distorted lose their natural 

 forms and the sides of the orifice are thrown into its own funnel, which con- 

 ducts the sound. TTe can, at pleasure, produce the buzzing by a contraction 

 of the muscles in the region of the ear, deforming thereby the channel to the 

 drum. 



Being fully satisfied of the validity of this theory of the sound of circulation, 

 and aware that many persons, partially deaf, hear an incessant rumbling, I am 

 convinced that it is occasioned by malformation of the orifice, or funnel to the 

 tympanum the projection of its sides causing the obstruction of other sounds, 

 and conveying its own buzzing of circulation, the same as from the inserted 

 fingers. An excess of ear wax may, however, produce a similar effect. Per- 

 sons of deficient hearing can learn whether it is an orifice defect by the 

 expansion therein of a pair of small pincers. 



ACTION OF SUGAR OX THE TEETH. 



M. Larez, of France, in the course of his investigations on the teeth, has 

 arrived at the following conclusions : 



1st. Refined sugar, from either cane or beets, is injurious to healthy teeth, 

 either by immediate contact with these organs, or by the gas developed, 

 owing to its stoppage in the stomach. 



2nd. If a tooth is macerated in a saturated solution of sugar, it is so much 

 altered in the chemical composition that it becomes gelatinous, and its 

 enamel opaque, spongy, and easily broken. 



3rd. This modification is due, not to free acid, but to a tendency of sugar 

 to combine with the calcareous basis of the tooth. 



OX THE UXITY OF THE HTJMAX RACE. 



In a discussion which incidentally arose on this subject at the last meeting 

 of 'the American Association, Prof. Agassiz made the following remarks : 



He regretted that this subject could not be discussed without seeming to 

 many to involve a religious prejudice. But he was bold to affirm that 

 differences exist between the races of men, greater than do exist between 

 animals of different species. Take the family of monkeys, our next cousins. 

 The monkeys constitute a family aU monkeys sharing the same structural 

 endowments, capabilities and propensities, even as men share theirs. The 

 monkey family is a unity, even as the human family is and no more so. I 

 never have denied the unity of the human family ; on the other hand I insist 

 upon it. Its unity is recognised in its physical, intellectual, and moral 

 endowments the three points of superiority over all other animals that con- 

 stitute its indivisible unity. And there is the same unity hi the monkeys ; 

 in them the same identity of structure, instincts, wants. 



And yet the Orang, the African type of monkey, is so different from the 

 Chimpanzee, the Asiatic type, that zoologists make them two distinct genera- 



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