CORRESP ONDENCE. 



115 



dies. In a country like ours," he would add 

 in a whisper, " the introduction of such a 

 system might prove murderous to some civ- 

 ilized beings." 



Dr. Black complains of my supercilious- 

 ness in preferring a charge of ignorance 

 against a contemporary who has for a long 

 series of years anxiously sought the solution 

 of " the problem how the sick can be made 

 well." Sad enough ; but that is no reason 

 why I should withdraw my charge. Dr. 

 Black may have sought that solution for a 

 most venerable series of years, but, unless 

 he holds his own time as cheap as that of 

 your readers, he ought to seek it more anx- 

 iously than ever, for it is very evident that 

 he has not yet found it. 



Felix L. Oswald. 



THE GEOLOGICAL DISTKIBUTION OF 

 FORESTS. 

 Messrs. Editors: 



IN discussing " The Geological Distribu- 

 tion of North American Forests," in your 

 August number (pp. 521, 522), Mr. Thomas 

 J. Howell makes the general statement that 

 the loess (or lacustral deposits) of the cam- 

 pestrian province " is devoid of trees," ex- 

 cept where cut through by erosion ; from 

 which he infers that " the loess is not ca- 

 pable of sustaining forest-growths for any 

 length of time." By way of explanation, i 

 he adds that the loess " evidently was tim- | 

 bered during the time that part of it was \ 

 covered by lakes and marshes," but, " when 

 the great rivers cut their beds down to 

 nearly their present level, the timber gradu- 

 ally died out." To generalization, inference, 

 and explanation, exception must alike be 

 taken. 



In much of Eastern Iowa, and in South- 

 eastern Minnesota, the loess is confined to 

 an irregular zone, five to fifty miles wide, 

 flanking the deeply eroded valley of the Mis- 

 sissippi on the west, and overlapping the 

 glacial drift which forms the greater part of 

 the surface of both States. The western 

 limit of this zone is exceedingly sinuous ; 

 lobes of drift extend for miles within its 

 general area, and narrow, finger-like belts of 

 loess, sometimes separating into isolated 

 outliers, extend still farther upon the drift- 

 plain. Now, this drift-plain is quite timber- 

 less ; but the loess is naturally wooded to 

 its extreme margin, and its outliers are also 

 generally wooded. The coincidence of for- 

 est-growth with loess is indeed so perfect in 

 this region that maps showing the wooded 

 area indicate with almost equal accuracy the 

 loess area. This is a region, too, in which 

 not only the "great rivers," but many of 

 their minor tributaries, have cut their chan- 

 nels through the loess, and far into the sub- 

 jacent roeks, thus developing the pictur- 

 esque river bluffs which lure so many tourists 



to the upper Mississippi region. A parallel 

 relation between loess and forests obtains 

 in Central and Southern Illinois. Here the 

 loess first appears, in passing from north to 

 south, as isolated mounds rising from the 

 almost dead-level drift-plain ; which mounds, 

 however far from other forests, are well 

 wooded. The Missouri River loess-belt is, 

 it is true, generally treeless, except along 

 water-ways, which may or may not, however, 

 cut through its deposits ; but natural tim- 

 ber is far more abundant than over con- 

 tiguous drift-areas, while its capability of 

 supporting arborescent vegetation is em- 

 phatically attested by the unprecedented 

 growth of artificially-planted fruit and for- 

 est trees, which is at once the marvel of 

 Eastern and the boast of Western horticul- 

 turists. The potent influence of geological 

 structure in determining the flora of any re- 

 gion is demonstrated by these relations of 

 loess and forests, especially in Northeastern 

 Iowa ; but the connection is directly oppo- 

 site from that which Mr. Howell seeks to 

 establish. 



But other and equally significant rela- 

 tions exist. Thus, it has been repeatedly 

 pointed out by the director of the Iowa 

 Weather Service, Dr. Gustavus Hinrichs, 

 that the lines of equal timber in Eastern 

 Iowa correspond remarkably, though in a 

 general way, with the lines of equal rainfall. 



Again, the origin of the loess is yet a 

 mooted point in geology, and the declaration 

 that its surface was once marshy is scarcely 

 warranted ; while no unequivocal evidence 

 that it was ever more heavily or continu- 

 ously wooded than now has ever been ad- 

 duced. 



The question as to the distribution of 

 forests, particularly in the campestrlan prov- 

 ince, is inextricably involved with that of 

 the treelessness of the prairies, concerning 

 which so much has been written, but con- 

 cerning which it is evident (since neither of 

 the relations pointed out in this note have 

 ever been adequately considered by those 

 who have addressed themselves to the prob- 

 lem) that the last word has not yet been 

 spoken. Mr. Howell would sever the Gor- 

 dian knot at a stroke ; but certainly some 

 of its strands have escaped his blade. 



Yours, W. J. McGee. 



WAsmsGTON, D. C, July 24, 1883. 



INFANTILE DT8PEP8LA.. 



Messrs. Editors : 



Referring to the very interesting pas- 

 sage at arms between Dr. Oswald, repre- 

 senting the natural, and Dr. Black, the anti- 

 natural school of medicine, while not desir- 

 ing to provoke further controversy, I bog 

 leave to offer a few remarks upon one point 

 at issue, viz., that pertaining to the alimen- 

 tation of infants. Dr. Black (see October 



