POPULAR MISCELLANY. 



6 33 



says the author, " is with some limitations 

 an expression of force." 



Cephalization is shown both in embryon- 

 ic development and in the progress of life 

 in geological history. The law is fur- 

 ther illustrated by the discoveries of Prof. 

 Marsh, from which it appears that the 

 brains of the great mammals of the early 

 Tertiary were very much smaller than those 

 of allied species of recent time. Thus the 

 brain of the dinoceras, of the Eocene, was 

 not more than one-eighth the size of that 

 of the modern rhinoceros, showing an im- 

 mense development of the brain, while the 

 bulk of the animals has decreased. We 

 have also a development of those features 

 of both form and capacity which are char- 

 acteristic of brain-power. 



The increase of the brain and nervous 

 system may arise, the author suggests, from 

 the fact that this part of the structure comes 

 in contact with outside and inside Nature, 

 and is the means by which the animal has 

 communication with the outer and inner 

 world, and with its own inner workings and 

 appetites. This constant and energetic use 

 of the brain may have given to it its won- 

 derful growth and strength since Eocene 

 times. 



But brain-progress could not have tak- 

 en place without structural progress, and 

 structural changes have been determined 

 by it. Brain-force reacts upon and modi- 

 fies both form and structure. 



It is not claimed by the author that the 

 theory of cephalization accounts for all the 

 types of structure found in the animal 

 world, but only that whatever these types 

 may have been in course of development 

 they were in general subordination to the 

 principle of cephalization. " The origin of 

 the grander types of structure," writes 

 Prof. Dana, " must be connected with the 

 profoundest of molecular laws ; and how 

 connected man may never know. These 

 views may hold, whatever be the true meth- 

 od of evolution. The method by repeated 

 creations should be subordinated, as much 

 as any other, to molecular law and all laws 

 of growth; for molecular law is the pro- 

 foundest expression of the Divine will. 

 But the present state of science favors the 

 view of progress through the derivation of 

 species from species, with few occasions 

 for Divine intervention. If, then, there has 



been derivation of species from species, 

 we may believe that all actual struggles and 

 rivalries among animals leading to 'sur- 

 vival of the fittest ' must tend, as in man, 

 to progress in cephalization and dependent 

 structural changes." 



On the Origin of Prairies. Having 

 shown, in an article which we noticed in the 

 December number of the Monthly, the 

 untenableness of the current hypotheses 

 with regard to the origin of prairies, Prof. 

 J. D. Whitney now presents, in the Amer- 

 ican Naturalist, a theory of his own. He 

 finds, as the result of a great number of 

 observations made over all the prairie States, 

 that almost without exception absence of 

 forests is connected with extreme fineness 

 of soil, and that this fine material usually 

 occurs in heavy deposits. " No person," 

 he remarks, " can have traveled through 

 Southern Wisconsin, Illinois, Iowa, or Mis- 

 souri, without having had everywhere occa- 

 sion to observe that the prairie-soil is ex- 

 ceedingly fine and deep ; there are whole 

 counties in Iowa in which not a single peb- 

 ble can be found." The distribution of the 

 timbered and prairie tracts in Wisconsin 

 affords a good test of the correctness of the 

 author's hypothesis. In the northern part 

 of the State is a region of dense forest, 

 though this is not a region of large precipi- 

 tation. It is, however, heavily covered 

 with coarse dettital materials, plentifully 

 distributed from the headquarters of the 

 drift on Lake Superior. The rocks under- 

 lying the drift-deposits are crystalline, be- 

 longing to the Azoic series, and the surface 

 is rough and broken, being intersected with 

 low ridges and knobs of granite and trap. 

 South of this is a large area, occupying the 

 central portion of the State, and extending 

 as far as the Wisconsin River, almost ex- 

 clusively occupied by a very pure siliceous 

 sandstone, which is wrapped about the 

 Azoic region, extending in a northeasterly 

 direction to the Menomonee River, and 

 northwest to the falls of the St. Croix. 

 This great sandstone-covered area is the 

 pine-district of the State, while south of 

 the Wisconsin is the region of oak-open- 

 ings and prairies. When we reach these 

 treeless tracts we have got entirely beyond 

 the drift-covered area, and are upon a soil 

 made up of the insoluble residuum left from 



