« PreviousContinue »
ancestor ; that this tendency was recessive; and that it could only be perpetuated by union with another recessive tendency of the same kind, supplied in this case by the visibly four-toed father. Selective breeding among the descendants has since “fixed” the type so that it
breeds true and adds yet another striking Two OF THE GROWN UP DESCENDANTS OF THE BLACK characteristic for the study of inheri
There are some characteristics, howrough; and if these dark and rough
cver, in which so far the Mendelian law guinea pigs are bred together a fourth
does not altogether coincide with the obcombination will appear in the grand
served results of scientific breeding, alchildren of the original couple. Some of though it is now believed that further inthese grandchildren will be white and
vestigation will discover another applicasmooth while others will represent the
tion of the same principle. Size is the combinations seen respectively in the
most important of these exceptions. parents and grandparents. By proper
Whereas color characteristics have been selection of parents any one of these
proved to vary with predicable uniformcombinations may be established as a
ity, size is apparently a permanent blend pure race of guinea pigs in which the children will invariably resemble their father and mother. Often also a new combination of characteristics obtained through experimental crosses will coincide with some long lost racial combination. The yellow rabbit mated with a black one may produce a certain proportion of little rabbits with the characteristic gray color of the wild progenitors of both father and mother. In the same way occur presumably those occasional surprising cases in human families when PRODUCED BY MATING DESCENDANTS OF BLACK AND
ALBINO Pigs. a son or daughter developes racial pecu
In their second generation the white color characteristic liarities not visible in either parent. If
contributed by grandfather pig appears in the
estimated proportion. their genealogies could be carried back far enough each parent would probably be found to possess an ancestor of the of inheritances. In a typical rabbit famrace to which the child had reverted- ily the size of the offspring is intermediSo, at any rate, we may deduce from the ate between that of the parents and none guinea pig
of the descendants revert to the extreme A A case of such reversion, for example, proportions of either grandparent. The has resulted in Dr. Castle's laboratory in practical result of this condition is that the evolution of a race of four-toed scientific breeding may produce at will a guinea pigs. The laboratory some years race of rabbits of any desired size beago came into possession of a male tween the known limits of size in rabbits, guinea pig whose four-toed feet made and with any conceivable combination of him unique among all the guinea pigs in color characteristics. The variation in the collection. There was no other like size is apparently continuous and depends him. And yet the four-toed guinea pig upon blending or striking a compromise one day surprised observers by becom- between the sizes of the parent rabbits. ing the father of a four-toed descendant. The variation in color depends upon the The mother was apparently normal. The scientific selection of parent rabbits in only explanation, therefore, was that she which the desired color characteristic is had inherited what might be called the not counteracted by any other. four-toed tendency from some distant These transmitted characteristics, it
will be seen, are invariably associated being, and the thoughtful observer with the parent at birth and are never naturally wonders about subtler inherit"acquired by the necessities of indi
ances than those of size and color. There vidual existence and then transmitted to is the question of inherited intelligence offspring. Dr. Castle's experiments, like and disposition—and this, in fact, is the those of many modern students of biol- next step in the study of the lower aniogy, tend to disprove the theory that ac- mals. Work is now in progress in Dr. quired characteristics can be transmitted. Castle's laboratory to investigate the efRather they confirm the conclusions of fects of a union between wild and tame Weissmann, which for twenty years have animals; the wild rat, for example, been the battle ground of biological opin- mated with a rat that has been domestiion, that the germ plasm, or reproductive cated by several generations of captivcells on which the continuity of all or- ity. These experiments are recent, but, ganic life depends, is independent of the so far as they have gone, they seem to body containing it, and that it is not influ- indicate that the strength and ferocity of enced by the characteristics acquired by the wild creature is the dominant charthat body during the space of a single life- acteristic according to the Mendelian time. This theory of inheritance casts an law. The offspring of the wild and the interesting and hopeful light on the sta- tame rat are in the first generation all tistics that are every now and then pub- apparently as wild as if they had been lished to show that the physical condition born of two wild parents, but when the of the average city-bred individual of offspring are mated the characteristics of today is inferior to that of his immediate the wild rat appear in modified form in ancestors. It would seem to indicate that some of the descendants while others such retrogression is not the result of in- seem to lack it entirely. These qualities heritance but of environment, and that are readily recognizable and the work of healthier living conditions in the large the psychologists with the various kinds cities, together with a wider distribution of apparatus they have invented for the of population back to the country, would study of intelligence in the lower anicounteract the tendency and produce a mals fortunately offers a means of excorresponding physical improvement. amination for mental characteristics that But it is also true, judging by these are more difficult to determine. The lower animals, that the statistics indicate psychological study of individual animals breeding from inferior family and racial and the psychological examination of stocks as a serious factor in the retro- their offspring and descendants for ingression of a startling number of indi- herited traits of intelligence is the next viduals.
step to be taken by these trained searchIt is still a far journey from guinea ers in the investigation of heredity by pig, mouse, rator rabbit to a human scientific breeding:
APTAIN MAYNE REID, ture. Some of Mr. Meyer's experiences
whose books have made nat- are akin to those of the three hunter uralists of more than one naturalists whom Captain Reid repreAmerican boy, once wrote a sented as having been sent out on like
story called, “The Plant errand by the authorities of the Kew Hunters." Its title was not particularly Gardens of London. alluring to the lads of the generation who The adventurous botanists of the old looked to their favorite for tales of pure tale were seeking specimens to be dried adventure, but before they had read long and preserved for museum purposes. they knew that they were to get excite- The adventurous botanist of the present ment with their botany.
tale cares nothing for the cut and dried. The heroes, there were three of them His is what David Fairchild of Washin the Captain's book, if memory's long ington, the Agricultural Explorer in shadow does not obscure the facts, were Charge of Foreign Seed and Plant Inon a plant hunting expedition in a valley troduction, calls a living work." of the Himalaya Mountains. The scene It is the duty of the man now in a of action was laid largely in wild places great desert of the Himalayan region to virtually geographically identical with secure seeds or cuttings of plants, shrubs those which are being searched today for and trees which he considers worthy of species of plant life by Frank N. Meyer, introduction into the United States, and an American field explorer working to get them quickly to Washington where under commission of the Bureau of Plant the work of propagation almost instantly Industry of the Department of Agricul- is started.
to hide some design on the peace of the government or the community. The specimen bag must hold some strange instrument of destruction, the more deadly because it is unknown. The experiences of botanists in the Eastern mountains, though with an added element of real danger, are like those of the peaceful opera glass ornithologist whose sanity is doubted and whose arrest is threatened by the country folk because he prefers to studythe living bird rather than to kill it, fill it with cotton and arsenic, and to pierce
it with wires for mounting HIGHLY RECOMMENDED AS A SHADE TREE IN THE ARID REGIONS OF OUR WESTERN STATES.
in painful and grotesque A drought-resistant species of poplar in Krasnawodsk, Turkestan.
Admittedly the expresExplorer Meyer is today in a lonely sion falls within the limits of what the land and before his mission is ended he objectors call the bromides, but it is the will pass through still lonelier lands. His desire of David Fairchild, the Agriculcollecting journey began at St. Peters- tural Explorer in Charge, and of his burg and it will end at some sea coast . fellow laborers in field and Capital, to port of Eastern China. His trip already make such deserts as the United States has been successful enough to make it has to blossom like the rose or, if not the worth much more than the money it has rose, the pear, the apple, the orange, the cost. He has frozen and melted alter
pomegranate or the olive. The nature
A plant hunter! Official
A Wild GRASS. APPARENTLY A SPECIES OF RYE. IN THE MOUNTAINS
NEAR BACHARDEN, TURKFSTAN.
of much of the land which is under search today for plant treasures is stony and forbidding, places apparently for the thistle and the thorn, and it would appear that he who looks for fruitage there must be one who thinks "yea” the answer to the question of Scripture, and that grapes may be gathered of thorns and figs of thistles.
The explorer now in the Himalaya Mountains carries in his head a botanical chart of the United States. He finds a species of plant useful or ornamental, or a variety of a species, and by reference to the mental map he knows instantly in what part of the United States it has a chance to flourish and to prove a blessing. He gathers with full knowledge of the locality in which one day Americans may sit under the shade of a Himalaya tree or gather fruit from a Himalayan vine.
In the plant hunter's head there is also a weather map. He knows the sections of the United States where long periods Frank M. MEYER. THE EXPLORER, IN THE HIMALAYA of drought would wither quickly any
MOUNTAINS. form of introduced vegetation whose life is moisture. He knows the places where large part the judgment of the plant the rainfall is apt to be excessive and he finder has been justified by results. knows where there are shadow and sun- Americans in the dry country of the shine in about equal parts. His is a work Southwest before long may pick from the of selection, and it can be said that in dooryard trees cherries whose flavor and
juiciness will make them forget the yearnings which they have had in the June time for the fruit of the tree which shadowed the New England home. Explorer Meyer found a wild species of cherry (Prunus microcorpa) growing and thriving on the dry moun
sides of Southern Chinese Turkestan. Perhaps in truth it must be called a bush rather than a tree for it is bush shaped and its height is not over ten feet. This cherry soon will be introduced into America.
In passing through the villages along the line of his journey it is Mr.
Meyer's habit to visit the AN AVENUE OF THE KARAKATCH TREE, A SPECIES OF ELM. fruit and vegetable stalls of Eminently fitted as a shade tree for the hot and arid, but irrigated sections of the United States.
the market places. While