974 



SCIENCE 



[N. S. Vol. XXV. No. 651 



10° to 46°. Of these constants only those at 

 the extreme limits of temperature vary from 

 the 2-3 limit set for the chemical reaction 

 constant. As to his own experiments oa 

 dogs, Herlitzka studied but few hearts, and 

 these apparently from dogs of all sizes and 

 weights, and compares results of hearts in 

 apparently all stages of nutrition, age, size 

 and state of injury. He then comes to this 

 conclusion (p. 286) : 



2°. L'aumento della frequenza delle contrazionl 

 eardiache non 6 una funzione costante della 

 temperatura, ma varia da un cuore all' altro ed 

 anche nello stesso cuore in varie fasi dell'esperi- 

 mento. A volte si tratto di una funzione lineare; 

 raramente e mai completamente la frequenza 

 teque la legge a cui soggiaciano le eomuni reazioni 

 chimiclie, gli enzimi, I'accrescimento ecc. 



As to what value should be placed upon this 

 author's work and his conclusions, this mu&t 

 be left to the decision of the intelligent 

 reader. 



In the paper already referred to the writer 

 has shown from llartin's results that the dog 

 heart obeys the law for chemical reactions as 

 closely as if one were dealing with pure chem- 

 icals. Not only when studied statistically, 

 then, but also when the individual heart of 

 the mammal is studied, is this found to be 

 the case. The same relation was shown to 

 hold for the rabbit heart and, in an unexpected 

 way, also for the human heart. 



While the thesis seems to be proved beyond 

 doubt the writer will be pardoned if he adds 

 still other evidence. 



Baxt' studied the effect of temperature upon 

 the dog heart primarily to find out the influ- 

 ence of temperature upon the action of the 

 vagus and accelerens nerves. But in record- 

 ing his results he always put down the tem- 

 perature and rate of the heart before stimula- 

 tion. So it happens we have in his paper 

 considerable data for further study of the 

 temperature coefficient of the 'normal' heart 

 of the dog. Under the conditions of his ex- 

 periment the temperature of the animals had 

 a tendency to fall off. By surrounding the 



' Baxt, Beriohte d. K. Saclisischen Gesellschaft 

 der Wissenschaft, Leipzig, Math, physik. classe, 

 1875. 



dogs with a double-wall chamber in which 

 water circulated the temperature could be 

 lowered and increased at will. Dogs of mid- 

 dle weight and in good condition were selected 

 for the experiments. The hearts were left 

 intact in the body, and artificial respiration 

 was maintained, the animals being poisoned 

 with curare. The temperature was varied ba- 

 tween 27.15° and 42.8° 0. 



Wherever a number of observations were 

 made, at about the same time, of temperature 

 and rates of very nearly the same value, the 

 writer determined averages for them. These 

 averages were compared with rates at lower or 

 higher temperatures and their coefficients in- 

 terpolated by the formula, 10RJR,(t^ — t,), 

 where B^ and R, are rates at the correspond- 

 ing higher and lower temperatures, t^ and t,. 

 These coefficients are: (1) From pages 339- 

 340, for 'A'— 2.18, 2.3, 2.0; for ' B '— 2.3, 2.7. 

 (2) From page 341, for 'A'— 2.2, 2.6; for 

 'B'— 2.5, 2.0, 4.3, 3.1, 3.6, 4.0. (3) From 

 page 342, for 'A'— 2.2, 2.0, 3.1, 2.5, 3.1, 2.0, 



2.4, 3.9; for ' B '— 1.7, 2.6, 2.7, 2.2, 2.2, 2.9, 

 2.6, 2.5. (4) From page 356—1.2, 1.8, 2.5, 



2.5, 2.0 1.7, 2.4, 2.6. 



Of the individual coefficients shown above 

 the lowest is 1.2, the highest 4.3; 71 per cent, 

 of them range between 2 and 3. The mean 

 average is 2.43. Verily, the mammalian heart 

 does follow the law for a chemical reaction 

 velocity as influenced by temperature. 



Charles D. Snydeb 



Berlin, 



the flanking detrital slopes of the moun- 

 tains op the southwest 



General Aspect and Grade of Detrital 

 Slopes. — The attention of travelers in the 

 southwestern portion of the United States is 

 arrested by the long and regular slopes of 

 gentle grade flanking the rocky ridges of the 

 mountains, and stretching in unbroken lines, 

 often for ten or twenty miles, across the line 

 of vision. Such slopes are most distinctly 

 developed in the Great Basin of Nevada and 

 the semi-desert Piedmont region of Arizona. 

 They give a striking and unique character 

 to the scenery, producing upon the beholder 



