MENDELIAN THEORY.

Otago Daily Times, Issue 19501, 9 June 1925, Page 11

MENDELIAN THEORY.

CENTENARY OF ITS DISCOVERER. . The first centenary of the birth of Father Johann Gregorions Mendel was celebrated all over the world a year or two ago by the Augustiuian Fathers, of which order lie was a member. In the “Ciudad de Dios - ’ Padre Francisco Marcos del Rio writes of the simple and modest life led by the discoverer of the Mendeliau laws, the most revolutionary contribution to biology since the studies of Darwin. Mendel's love for botany was hereditary, as his father was devoted to gardening, and his first scientific communication was ‘•Experiments in Hybrids.” Mendel experimented on animals and on bees. By a strange coincidence Father Marcos del Rio recalls three botanists (Correns, De Vries, and Tschermak) published in 1000 simultaneously and independently the work done 40 years before by the great Augnstinian friar. The I’itsum salivium (common garden pea) was the favourite plant of the experiments, because it is immune from crossed fecundation on account of its stamen and pistils being enclosed in its petals, and because its varieties arc very constant and distinct in their characteristics. The laws which are held as constituting a high perconl.age of probability in heredity by scientists are roughly speaking three: —(1) The law of the predominance, or prevalence of the Mendeliau characteristics; the fertile hybrids produced by two parents belonging to different races or varieties of the same species or of two nearly related species will inherit the dominant characteristics and preserve in a latent state the retrogressive characteristics; (2) The law of the disunion of the Mendelian characteristics: Supposing that the dominant and subjective characteristics were joined in the hybrids of the first generation: they will bo separated ia the hybrids of the second generation in such a way that the predominant characteristics will reappear in the individuals and the secondary characteristics will be seen only in one-fourth of the other individuals of the same descent; (3) The law of the independence of the same characteristics; Counting from the second gene ration the hybrids born with the secondary or subjective characteristics will not lose them even though they propagate and reproduce themselves indefinitely; but they are different from their type only by reason of their origin, having merged for all practical purposes into the normal type again. Tllb far-reaching significance of those laws when applied to the breeding of higher animals and man, especially in the study of hereditary mental and physical taints is obvious. The Mendelian doctrine, the Spanish Angnsitiniau concludes, forms the most vigorous refutation of the conclusions of Darwin.