INTERNATIONAL CONFERENCE ON PLANT BREEDING. 419 



In conclusion, Bateson says : — " We have at last a clear notion of the 

 meaning of purity or fixity of type, of the consequences of dominance, 

 and of the nature of heterozygous forms — phenomena which go to make 

 up the daily experience of those who are practically engaged in these 

 pursuits." . . . M Apart from the profounder mysteries, the unravelling 

 of the problems of heredity has now become a matter for simple statistical 

 research." ..." We may confidently look forward to the time when the 

 laws of heredity, hitherto a hopeless mystery, will in their outward pre- 

 sentments, at least, be as the laws of chemistry now are, a matter of 

 everyday knowledge." 



Notes on Mendel's Methods cf Cross-Breeding. 

 By C. C. Hurst, of England. 



This paper gives a brief outline of Mendel's methods in planning and 

 carrying out his classical experiments with Peas. Mendel obtained 

 definite results by taking each single character separately as a distinct 

 unit, ignoring for the time being the individual plant made up of many 

 characters. In this respect Mendel apparently was the first experimenter 

 to recognise the importance of unit-characters. Mendel worked only with 

 the constant diameters of fixed races, thus eliminating all questions of 

 ancestry as regards those particular characters. Mendel selected for 

 crossing characters that were distinctly differential in the two parents, so 

 that they could be clearly defined in the offspring of the subsequent 

 generations. Mendel worked with pairs of unit-characters, one of which 

 was always dominant over the other, which was recessive. This gave 

 uniformity in the first generation, and avoided the difficulty of working 

 on to the following generations with results that were not uniform. 

 Mendel raised large numbers of plants in each generation, taking care to 

 regard separately the offspring of each individual plant or type. Mendel 

 was not content to stop at the first or even the second generation, as so 

 many of his predecessors were, but in all cases carried on the experiments 

 to the third and fourth generations, and in some cases to the fifth and 

 sixth. 



To sum up, those who desire to follow in the footsteps of Mendel, and 

 help to elucidate the baffling problems of heredity, will find it essential to 

 select parents possessing characters which are at once single and constant, 

 differential and dominant, and they will also take care to raise large 

 numbers of individuals through many generations, regarding separately 

 the offspring of each individual. By thus following Mendel's methods 

 definite results will assuredly be obtained. 



On Artificial Atavism. By Hugo de Vries, of Holland. 



Professor de Vries gives an account of his experiments in crossing two 

 constant races of the Snapdragon {Antirrhinum majus) and the behaviour 

 of the hybrids in subsequent generations, which, he says, " gives an entire 

 confirmation of Mendel's predictions." 



In the first generation White x Red gave all hybrid Reds like the 

 Dark Red parent. In the second generation the hybrid Reds self -fertilised 

 gave rise to four types, which are classified as Dark Red, Flesh-coloured, 



