ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 19 



sea-water is of more importance. The specific gravity may be diminished 

 by accumulating water or gelatinous material. An increased effect may 

 be given to the viscosity of the water by the development of spiny or 

 feathery outgrowths. The economic importance of the plankton is 

 incalculably great. Thus each food-fish is dependent upon a food-chain ; 

 the organisms forming any link of the chain supporting those of the 

 next link and being themselves dependent upon the next link in the 

 other direction, while the chain ends in the physical conditions of the 

 sea-water. A serious diminution in the numbers of fish in a given 

 locality may be a fluctuation due to a weakening of a link in the food- 

 chain. Or it may be due to migration away from accustomed haunts in 

 company with shifting of the physical conditions suitable to one or 

 other link. A scientific knowledge of the plankton must form the 

 basis of practical action in such cases. 



Changes in Breathing and Blood at High Altitudes.* — M. P. 

 Fitzgerald publishes a record of further investigations into the changes 

 in breathing and blood at high altitudes. Her present investigations 

 were made on persons acclimatized up to 3850 ft., and the results con- 

 firm those gained in the earlier study, which included persons acclimatized 

 from 5000 to 14,000 ft. The lowering of the C0 2 pressure is in direct pro- 

 portion to the diminution of the barometric pressure, and amounts to 

 about 4 - 2 mm., or 10*5 p.c. of the sea-level value for each 100 mm. of 

 diminution of barometric pressure. In women, as at sea-level, the 

 alveolar C0 2 pressure is about 3 mm. lower than in men. The per- 

 centage of ha?rnoglobin in the blood is increased at altitudes of 3850 ft., 

 as at higher altitudes. For every 100 mm. fall of atmospheric pressure 

 the percentage of haemoglobin in the blood is increased by about 10 p.c. 

 of the normal value for men at sea-level. In women, as at sea-level, 

 the values are about 11 p.c. lower than for men, but greater irregularity 

 is observed. Graphic representations and tables of the results are given. 



Facial Vibrissas of Mamm iis.t — R. I. Pocock finds that in all the 

 principal orders of terrestrial Mammals some, at all events, of the species 

 possess facial vibrissa? arranged upon a definite plan. In a great many 

 cases, within the limits of a certain order, the species which are defective 

 in the matter of vibrissa? are the higher derivative types, whereas those 

 in which all or most of them are present are the more generalized types. 



Except perhaps the suboculars, vibrissa? are primitive Mammalian 

 features. They are disposed in five groups. — 1. The buccal, including 

 mystacials on the muzzle and upper lip, and the submentals on the chin 

 and lower lip. 2. The interramal, an unpaired tuft of bristles, often 

 symmetrically arranged, projecting from the interramal area behind the 

 mandibular symphysis. 3. The genal, consisting of one or two tufts, 

 or isolated bristles on the check. 4. The superciliary, forming a tuft 

 over the eye, generally over its anterior portion. 5. The subocular, 

 beneath the eye, mainly in large Herbivora. The superciliaries and 

 suboculars must not be confounded with the eyelashes. The vibrissa? 



* Proc. Roy. Soc, lxxxviii. (1914) pp. 248-57 (2 figs.). 

 t Proc. Zool. Soc, 1914. pp. 8*9-912 (13 figs.). 



C 2 



