ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 47 1 



substances or hormones which circulate through the body, and acting 

 on the gametes stimulate those parts of them which are destined to 

 develop the same parts in the next generation. Secondary sexual 

 characters, such as antlers and mammary glands, are supposed to have 

 been produced, as modifications, at the time when the gonads were 

 giving off their hormones, and thus the tendency, which is inherited, is 

 to develop these modifications in the presence of those hormones, and 

 not otherwise. 



Phosphorous Content in Different Types of Animals.* — Hilda 

 Kincaid finds from analysis of the exoskeleton in each class of Inverte- 

 brates that there is a steady increase in the phosphorus content as we 

 ascend the evolutionary scale. It is never at any time large in Inverte- 

 brates, for most of the framework in lower animals consists of CaC0 3 , 

 while that of higher animals consists of Ca 2 (P0 4 ) 2 . In the endoskeleton 

 of Vertebrates there is a sudden jump in the phosphorus content, which 

 remains practically the same through the group. Analyses showed that 

 the phosphorus content of nerve tissue and muscle tissue has a surprising 

 uniformity throughout the whole animal kingdom. 



Circulation Rate in Man.f — Walter M. Boothby brings forward 

 experimental evidence showing that the circulation rate increases pro- 

 gressively with the oxygen consumption per minute in a manner corre- 

 sponding to the increase in the total ventilation. The circulation of the 

 blood is as carefully and delicately regulated in relation to the needs of 

 the body as is the ventilation of the lungs. It is probable that the 

 same regulatory factor — the hydrogen-ion concentration of the arterial 

 blood — controls with equal delicacy the ventilation of the lungs and the 

 rapidity of the circulation rate. Factors of nervous or psychic origin 

 influence the circulation and pulmonary ventilation, but such influences 

 are only temporary, and designed to meet sudden emergencies which 

 require immediately in the muscles a greatly increased oxygen supply 

 before a sufficient time could elapse for the chemical stimulus to be 

 produced and to take effect. 



An increase in the blood flow of 3 ' 3 litres per minute, which is a 

 doubling of the circulation rate, is caused by a rise in the total acidity 

 of the blood corresponding to 2 mm. of carbon-dioxide, and this would 

 correspond to a rise in the hydrogen-ion concentration of the arterial 

 blood of about 0-013 x 10~ 7 . 



Colubrid Snake with Vertically Movable Maxillary Bone.i — 

 E. G. Boulenger finds that the solid-toothed Colubrid, Xmodon merremi, 

 from Brazil and Paraguay, is able to erect and depress its fangs in a 

 thoroughly viperine fashion. The portion of the maxilla bearing the 

 fan°;s is much enlarged, and in a more or less vertical direction. It onlv 

 remains for the last two teeth to be furnished with grooves to transform 

 Xmodon into an Opisthoglyph, with the fangs situated below the pre- 



* Eep. British Assoc, Australian Meeting, 1915, p. 554. 

 f Amer. Journ. Physiol., xxxvii. (1915) pp. 382-417. 

 t Proc. Zool. Soc, 1915, pp. 83-5 (1 fig.). 



