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MENDES


182


MENDES


third generation are allowed to be self-fertilizecl, it is found that all the recessives (dwarfs) breed true and, wliat is more, will go on breeding true as long as iHiinlerfered witli. Xot so the dominants, which, after self-fertilization, produce both tails and dwarfs. Some of the tails of this generation will breed true and continue to breed true; others will not, but will produce a mixed progeny. Hence, out of the first plants, seventy-five will be tails (dominants), and twenty-fi\'e dwarfs (recessives), these last being pure. Of the seventy-five tails, twenty-five will be pure and will go on producing tails; fifty will be mixed, and their progeny will consist of pure dominants, mixed dominants, and recessives, as has been stated above.

Davenport thus enunciates the laws underlying these facts: "Of the two antagonistic peculiarities possessed by two races that are crossed, the hybrid, or mongrel, exhibits only one; and it exhibits it completely, so that the mongrel is not distinguish- able as regards this character from one of the parents. Intermediate conditions do not occur. . . . Second: in the formation of the pollen, or egg-cell, the two antagonistic peculiarities are segregated; so that each ripe germ-cell carries either one or the other of these peculiarities, but not both. It is a result of the second law that in the second generation of mongrels each of the two qualities of their grand- parents shall crop out on distinct individuals, and that the recessive quality shall appear in twenty-five per cent of the indi\'id"uals, the remaining seventy-five per cent having the dominant quality. Such re- cessive individuals, crossed inter se, should never produce anything but recessive offspring."

Such, in brief, are the main outlines of Mendel's theorj-; but in the few years which have elapsed since it first engaged the attention of the scientific world, there has grown up an enormous literature on the subject which has much added to the com- plexity of the minor developments of the laws above enimciated, and has still more added to the difficulty of the terminology of Mendelism. With these developments it is impossible to deal here: they will be found very fully treated in Bate- son's work (see below). It would, however, be negligent to omit all mention of the estimation in which the theory itself is held by men of science of the present day. Bateson claims that "his ex- periments are worthy to rank with those which laid the foundation of the atomic laws of chemis- try"; and Lock, that his discovery was "of an importance little inferior to those of a Newton or a Dalton ' '. Punnett also states that, owing to Mendel's labours, "the position of the biologist of to-day is much the same as that of the chemist a century ago, when Dalton enunciated the law of constant proportions. In either case the keynote has been Discontinuity — the discontinuity of atom and the discontinuity of the variations in living forms". It is a remarkable fact that Mendel's writings never appear to have come under the notice of Charles Darwin, and many have speculated as to the effects which tliey might probably have exercised on that writer had he made their acquaintance. T. H. Morgan does not hesitate to say that Mendel's laws give the final coup de grace to the iloctrine of Natural Selection, and others consider that his views, if finally proved to be correct, will at least demand a profound modification in the theories associated with the name of Darwin.

It would not, however, be by any means correct to suppose that Mendel's views have been received with complete acceptance by the scientific world; indeed there is a sharp, and at times even embittered, controversy between the supporters of Mendel and his opponents, amongst wiiom the late Professor VVeldon may perhaps be considered to have been one


of the most important. The end of the controversy is not yet in sight, nor is it likely to be for some lime, judging by the extraordinarily varied results which observers ha\e drawn from e^■en identical series o[ facts. For instance, from the sanu; materials afforded by the colom-s of thoroughbred horses given in the pages of Weatherby's "Ocneral Sludbookof Horses", a Mendelian (Mr. Hurst) has deduced evidence in favour of the view which he upholds, and an anti- Mendelian (the late Professor \^ eldon) has arrived at a diametrically opposite conclusion. This, at least, may safely be said: that Mendel's views have been endorsed by a number — it would probably be safe to say a steadily increasing number — of scientific men ; that they seem to be likely to exercise a profoiuid infiuence on agriculture and on the scientific breeding of horses and stock ; and that, with such modifications as farther experience may suggest, the main underly- ing principles of the work will probably become more and more firmly established.

As above stated the papers in which Mendel's the- ories were made public are contained in the " Pro- ceedings" of the Briinn Society. They have been made availabl.' for English readers by the translation which appears in Bateson's work (see bibliography below).

Bateson, Mendel's Principles of Heredity (Cambridge, 1909) (this is the most important v/ork in English, and contains a translation of Mendel's papers and a biography as well as a full account of all recent work on Mendelian lines); Pdnnett, Mendelism (Cambri^Ige. 1905), a good brief account of the sub- ject; Lock, Recent Progress in the Study of Variation, Heredity and Evolution (London. 1906); \yAi.SH. Catholic Churchmen in Science (Philadelphia, 1906). .See also Royal Society Reports on Evolution. In Bateson*s book, and in Kellog, Darwinism To-Day (New York, 1907), many references to foreign periodi- cal literature on the subject will be found.

B. C. A. WiNDLE.

Mendes de Silva, Jo.To, better known as Amadeus of Portugal, b. 1420, d. at Milan, 14S2, began his re- ligious life in the Hieronymite monastery of Notre- Dame de Guadalupe (Spain), where he spent about ten years. Desirous of joining the Franciscans, he went to Italy, where after some delay he was received into the order and, living in various convents, chiefly at Milan, attracted attention by his virtue and miracles. Under the protection of the Archbishop of Jlilan, he established the convent of Notre-Dame de la I'aix (1469) which became the centre of a Fran- ciscan reform. The minister general of the order, Francesco della Rovere, later pope under the name of Sixtus IV, extended his protection to him. Other fotmdations were made in Italy, among them one at Rome. Supernatural favours obtained through his intercession aided in the spread of his cult, and the BoUandists testify to the authenticity of the title . "Blessed" bestowed on him. He composed a yet unpublished treatise entitled "De revelationibus et prophetiis", two copies of which are mentioned by Nicholas Antonio. The work of another Amadeus, "Homilies on the Blessed Virgin", has been errone- ously attributed to him. The convents he founded continued after his death to form a distinct branch of the Franciscans ; the friars were called the Amadeans or Amadists, and they had twenty-eight houses in Italy, the chief one, Saint Peter de Mont orio, in Rome. Innocent VIII gave them the convent of Saint Genesto near Cartagena in Spain (1493). The successors of Blessed Jo;lo, Georges de Val-Camonique, Gilles de Montferrat, .lean .A.llemand, Bonaventurade Cremona, preserved his foundation in its original spirit until Saint Pius V suppressed it along with similar branches of the Franciscan Order uniting them into one great family of Friars Minor Observants (1568).

Arta SS., August, II, .562-606; Antonio, Bibliotheca vetua hispana. II, 217-18; Wadding, Annates Minorum, \I, VII, VIII; Helyot, Hisloire des ordres religietix, VII, 106-12,

J, M. Besse.