April 15, 1892.] 



SCIENCE. 



221 



the case, there is more agreement than difference in our discus- 

 sion. 



My misapprehension arose as follows : In his essay of Jan 29, 

 after speaking of headwater erosion and the subsequent capture 

 or lateral abstraction of certain streams by this process, Professor 

 Hicks wrote, " The latest robbery in the Loup system is that of 

 the headwaters of the Wood Eiver. Journeying down, from the 

 headwaters of the South Loup, one is impressed with the apparent 

 continuity of its valley with that of Wood River, rather than with 

 that of the South Loup itself below Callaway. It is obviously an 

 instance of the lower, more easterly stream cutting through the 

 divide and drawing to itself the headwaters of the higher one. 

 This series of captures by lower tributaries is exhibited on a grand 

 scale and in a mature form in the Loup system." 



If the reader will refer to the first figure in Professor Hicks's 

 essay, he may understand why I inferred from this sentence that 

 the several other deflected streams, exhibiting the same relative 

 parts as shown in the South Loup and Wood Rivers, constituted 

 the ' ' series of captures " in which the South Loup was " the latest 

 robbery." 



It now appears, however, that the head of Wood River was not 

 precisely located in the figure referred to; and that its correction 

 by Professor Hicks in his letter to me places it more as figured by 

 Professor Todd in Science for March 11. As thus figured, it is dis- 

 tinctly placed in another category from the streams deflected east- 

 ward by flood-plaining. 



Professor Hicks refers me to his article on "An Old Lake Bot- 

 tom '■ in the second volume of the Bulletin of the Geological 

 Society of America. Mention is there made of certain old valleys 

 - of Tertiary erosion, more or less obscured but not entirely con- 

 cealed by lake sediments of later Tertiary deposition, by which 

 the country is now covered. These old valleys are placed in the 

 same category with the abandoned channel at the head of the Wood 

 River, by which the South Loup is supposed once to have flowed 

 to the Wood, as if headwater erosion by adjacent streams had in 

 all these cases determined the abandonment of the old valleys. 

 But it is still not clear why all these abandoned valleys must be 

 regarded as having lost their former streams by lateral abstraction 

 following headwater erosion. I perceive that the slopes indicated 

 in Professor Hicks's figures are in the proper direction for such 

 abstraction ; but it is surprising to find that slopes of so moderate 

 a measure of inclination sufiSce to give one stream an advantage 

 ■over another, even to the points of abstraction of this kind. I 

 shall be delighted if this is proved to be the case; for, if so, the pro- 

 cess of abstraction and the accompanying rearrangement of divides 

 may be regarded as of very extensive application. As ordinarily 

 ■explained, the advantage that the capturing stream must possess 

 is much greater than would be found in a region of horizontal 

 and comparatively weak sediments, and of moderate inclination, 

 such as Nebraska. 



I shall therefore hope to have a fuUer discussion of the problem 

 from Professor Hicks, and an exclusion of other processes as 

 well as a confirmation of the effective action of headwater erosion 

 on so large a scale in producing these changes in Nebraska river 

 courses. 



The chief rearrangement of the Loup streams, as shown in Pro- 

 fessor Hicks's diagram, being the product of down-stream deflec- 

 tion of the tributaries of a flood-plained river, I find in them a 

 very satisfactory justification of a somewhat hazardous explana- 

 tion offered in an essay on the Rivers and Valleys of Pennsylvania 

 (Nat. Geogr. Mag., I., 1889, 241) for the down-stream deflection 

 -of certain tributaries of the Susquehanna in the central portion of 

 the State. But in this case the flood-plain, by whose growth the 

 tributaries were deflected, is a thing of the imagination. If it 

 ever existed, it has been entirely worn away by the denudation 

 following the later elevation of the region in Tertiary time ; the 

 deflected streams, maintaining their specialized courses after up- 

 lift, cut down their channel through the imagined flood-plain 

 .sediments, and thus became superimposed on the underlying 

 strata, which they now deeply dissect and traverse in a highly in- 

 consequent manner. Professor Todd's diagram gives further 

 illustration of this kind of down-stream deflection of tributaries. 

 All of the branches of the Platte are deflected before reaching the 



main stream ; the Platte itself is turned down before Joining the 

 Missouri; so is the Niobrara. 



In this connection I wish to suggest another cause besides the 

 three mentioned by Professor Todd for the north-eastward turn of 

 the Platte at Kearney ; namely, the possible spontaneous deflection 

 of the river from its previous more direct course, as, for example, 

 along the Little Blue, by its own action in building up the plain 

 over which it flowed. The rivers of the plains of India frequently 

 change their courses in this fashion ; the Hwang- ho devastates the 

 plains of China for the same reason. May not the Platte have 

 once had the same shifty habit? The Garonne, in south-western 

 France, is a still more striking example of a spontaneous avoidance 

 of its former course. Much of the waste borne out from the 

 Pyrenees by the Garonne and its fellows now forms a flat, delta- 

 like surface, of radial slope from the point where the larger rivers 

 issue from the mountains; but, instead of pursuing a direct course 

 northward, the Garonne turns sharply to the east at the foot of 

 the mountains; while numerous small streams run down the slope 

 of the radial alluvial deposit. Perhaps in the same way the 

 Little Blue and the branches of the Big Blue Rivers may represent 

 the old courses of the Platte, abandoned for a newer course of 

 lower grade. 



There are two other questions that I should like to ask of western 

 observers. Is there generally perceptible a right-handed deflec- 

 tion of the rivers on the plains, as if in consequence of the earth's 

 rotation? Can examples be given of the lateral abstraction of one 

 stream by another on a slope of planation, after the fashion de- 

 scribed by Gilbert in his report on the Henry Mountains some 

 years ago? W. M. Davis. 



Cambridge, Mass., April 7. 



The Persistency of Family Traits. 



There are one or two points bearing on the subject at the head 

 of this article that were not mentioned by either of the writers in 

 the issue of March 18. The first is that the mother in placental 

 mammals tends to assimilate in respect to blood to the father, as 

 the blood of the mother passes through the young in utero and 

 therefore the strain of blood derived from the father is shared by 

 the young with the mother. A study of family history carried 

 on for almost twenty-five years shows that there is generally a 

 running to what are called "family types" among the youngest 

 of a numerous family, and the type is that of the paternal family. 

 It is too well known to need argument that the mother frequently 

 acquires diseases belonging to the father indirectly through the 

 child she is carrying. It is also well known that an old couple 

 tend to assimilate in facial and bodily appearance, and the change, 

 as shown by numerous instances, is generally in the female, as 

 the above facts would call for. We can see that each child in a 

 family finds the mother more and more impregnated with the 

 blood of the paternal house, and it is not strange if the children 

 favor the family that gives them the name. 



The other fact is that the pregnant mother is more readily in- 

 fluenced by whims than in any other state. From classical times 

 to the present it has been the aim of those about a woman in such 

 a state to make life as pleasant as possible. While we may no 

 onger surround her with beautiful statues and other paraphernalia 

 of a Roman household, we recognize that her whims may fix the 

 character as well as permanently mark the coming child. We 

 drive a gravid mare in a light wagon that the foal may be amena- 

 ble to discipline. As the generality of married people associate more 

 with the family that carries the name, it follows that the mother is 

 affected by sympathy or antipathy for that family, and both lead 

 her to dwell on the features and forms of its members, so that the 

 child runs a good chance of bearing either or both. Birth-marks 

 dcfnot exist in fiction only, and though the bloody horse-shoe of 

 Redgauntlet may be lacking, there are other signs to show the 

 horror or antipathy of a terrified or whimsical mother. In a love 

 match, the face of the father is reproduced, or, as the French 

 proverb says, " The love child resembles the father." A union, 

 therefore, of the two conditions noted above will cause the chil- 

 dren to favor the race that carries the name rather than to run 

 toward the spinster side, even were there nothing like reversions 



