22 INEZ L. WHIFFLE. 



the drop. Evidently the crescentic fold had been withdrawn as 

 usual but the cessation of the usual function of the groove had 

 resulted in the fluid entering the naris. This inference was proved 

 correct by an examination of the interior of the mouth in which 

 the carmine was found. 



In the light of these experiments the process of freeing the 

 nasal depression from water may be explained as follows : 



When, after the excess of water has flowed off from the gen- 

 eral surface of the head, a small amount is left in the nasal de- 

 pression, its surface tension is too great to allow its removal 

 merely in obedience to gravitation. There is, therefore, a most 

 delicately adjusted combination of devices by means of which 

 gravitation is aided and the rapid removal of the water from the 

 naris is effected. These are (i) the capillarity of the groove 

 which is, especially at its nasal end, very narrow and deep ; (2) 

 the continuity through the medium of the groove, of the water in 

 the nasal depression with the water at the labial end of the 

 groove, even though this may be merely a larger drop which has 

 accumulated on the surface of the lip; (3) the final impetus to 

 flow down the groove, given by the wrinkling back of the cres- 

 centic fold in the process of opening the naris. It is impossible 

 to say which of these factors is of chief importance. When the 

 amount of water is very small, probably either the first or the 

 last alone would suffice. With a larger amount of water the 

 deeper portion of the groove quickly fills by capillary attraction 

 and then its outer, wider portion probably serves merely as a 

 gutter down which the water flows by gravitation. That the 

 capillarity of the groove, working in the reverse direction, does 

 not prove a disadvantage is due to the fact that the groove is 

 continuous with the external surface of the crescentic fold which 

 is, therefore, the only part affected. 



Although the nature of the secretion of the glands has not been 

 chemically tested, their function is obvious. The only portion 

 of the head over which water does not flow freely and from which 

 water seems in fact to be repelled is the region immediately sur- 

 rounding the naris and the mesial border of the groove. In these 

 regions microscopic sections show a noticeable lack of the large 

 acinous glands of the skin, the secretion of which readily mixes 



