RESEARCH SEMINAR. 247 



emphasized although he is inclined to believe that they are very 

 important factors in evolution. The second factor which is a 

 form of isolation, namely tendency to self-fertility or prepotency 

 of pollen, would be present whenever the flowers of the plant are 

 modified to insure self-fertilization, as in the case of the pea, bean, 

 and many other legumes, in wheat, barley, and some other 

 plants, and in cases which may occasionally occur where the 

 mutation gives rise to a plant which has a strong tendency 

 towards self-fertility, the progeny of cross fertilization with pollen 

 of another individual being fewer in number and lacking in vigor. 

 Such a mutation was observed and experimented with by Darwin 

 and graphically described under the caption " The Hero Morn- 

 inglory." ' The races of Cupid sweet peas, and various wheat 

 races are illustrations of cultivated species, we may call them, 

 that have originated in this way. Given a mutation suited to the 

 environment, having strong transmitting power, and a tendency 

 to self-fertility, or some device insuring self-fertility and we have 

 the creation of a new species. 



The third means by which the swamping effect of panmixia 

 may be overcome is where a tendency to prepotency or prepond- 

 erance of type is formed. In such instances the mutation, giving 

 rise to a type which while not necessarily preferring self-fertiliza- 

 tion is strongly prepotent and dominant in its action and trans- 

 mits its characters to all its progeny which bred inter se, would 

 probably strengthen the type and lead to its gaining a permanent 

 foothold. Such illustrations, like the Ancon or Otter sheep are 

 not uncommon among domestic animals and plants. 



July 30. The General Laws of Hybrids with a Discussion of 

 Mendel's Principles. By HERBERT J. WEBBER. 

 The claim advanced by Mendel and some of his followers that 

 of a certain allelomorph or character pair, one character is domi- 

 nant and masks the other character in first generation hybrids 

 was claimed by the speaker to have but limited application. 

 Many cases of blends of two characters were cited. It was also 

 pointed out that the statement that first generation hybrids are 

 of the same type is erroneous. The case of hybrids of orange 



1 Darwin, Cross and Self-fertilization in the Vegetable Kingdom," p 47. 



