566 Scientific Intelligence. 



Subjects which stand in the middle between a number of 

 sciences are likely to have important bearings upon all, and yet, 

 since their investigation requires the ability to evaluate evidence 

 outside of each specialty, their weight is slow to become appre- 

 ciated. 



As yet, however, the work is largely preliminary. There can 

 be no doubt but that climatic fluctuations measured by centuries 

 have taken place, but just what difference this means in mean 

 annual rainfall, or just how large a factor this is in stimulating 

 the migrations of peoples, is a matter upon which no unanimity 

 of judgment has been reached. But for these very reasons the 

 subject is one of the first importance and demands an extension 

 and intensification of the investigation. Great credit is due to 

 Dr. Huntington for the energy and courage with which he has 

 explored distant regions of the earth, for the direct and varied 

 studies of nature, and for the originality of conceptions which he 

 displays in his work. 



It would appear that the investigation of the growth-curve of 

 the sequoias should be followed up in the immediate future. 

 Huntington, in his work, employed a method of averaging 

 together a large number of measurements from stumps. But the 

 sequoia is very sensitive to environment, as shown by its restricted 

 range. Consequently the character of slope exposure, elevation 

 above the sea, depth and quantity of ground water would have 

 marked influence. A slight climatic change toward aridity 

 would affect unfavorably the trees on sunny slopes or low alti- 

 tudes, while it might affect favorably, or not at all, trees situated 

 at the upper limits of growth, or growing on shaded or better 

 watered tracts. This is probably in considerable part the explana- 

 tion of the great individual variations shown in the growth. If 

 the stumps were classified according to careful studies of the 

 environment, and only selected stumps used in each, the record 

 would very probably become more clear. Particular cycles of 

 years might be identifiable in different stumps, as Douglas was 

 able to identify them, for the nineteenth centuiy in Arizona. 

 This would not only fix definite time markers by means of indi- 

 vidual years and sequences of years, but would give a much 

 closer and more detailed record of climatic conditions in Cali- 

 fornia extending backward to the era of the Trojan war. 



Statistical studies of the age of trees in each division of envi- 

 ronment should also be made, for during a time of dryness few or 

 no new trees would start to grow on the areas most adversely 

 affected. During times of cold and wetness the opposite limiting 

 areas would be expected to show few beginnings. A progressive 

 regional shift in the optimum would also be expected. It is for 

 the determination of the long and slow progressive changes that 

 such a method if applicable would be most valuable, and it is for 

 just such changes that the individual stumps are of least value, 

 for the growth curves of the trees are affected by the changes in 

 rate due to the passage from youth to age. Furthermore, the 



