QUANTITATIVE METHOD AND PRIMORDIA 35 



The segregation of each pair of properties has taken place as 

 if the other pair did not exist. In respect to the pair D, R the 

 plants are divided into two groups D and R ; in each of these 

 the plants are divided in their turn into two groups d and r — viz. 



F, 



D R 



d r 



Visible properties . . Dd Dr Rd Rr 



Groups ....ay j8 6 



In another experiment MENDEL crossed two subspecies 

 which differed in three properties of the ripe seeds — viz. 



Subspecies a : seeds round [D], albumen yellow [d), seed- 

 coat grey-brown (8). 



Subspecies b : seeds wrinkled (R), albumen green (r), seed- 

 coat white (p). 



In the Fg generation eight sorts of seeds were obtained : 

 DdS, Ddp, DrS, Drp, Rd8, Rdp, RrS, Rrp. All the results were 

 governed by the same rules as the two first experiments. 

 (Complete explanation is given in § io6.) 



In a similar way as QUETELET'S work, the discovery of 

 MENDEL passed unnoticed for a long time. Even the famous 

 NAGELI failed altogether to realize the importance of it.^ 

 About 1900 MENDEL'S paper was discovered almost simul- 

 taneously by three botanists, CORRENS, TSCHERMAK and 

 DE VRIES. These three repeated independently from each 

 other MENDEL'S experiments and confirmed his results. 



Since then numerous researches along the Unes initiated by 

 MENDEL have been carried out. A number of experiments 

 have given results similar to those arrived at by MENDEL. 

 In other cases the results of hybridization are more comphcated. 

 Several of these, however, have already been elucidated. 



MENDEL has added to biological science a new branch 

 (Mendelism) which is remarkable by the rigour of its reasoning 

 and the exactitude of its conclusions. Both qualities are the 

 result of the use of the quantitative method, based here upon 

 counting in each generation the specimens in which the pro- 

 perties of the crossed subspecies are visible, latent or vanished, 

 and comparing the figures.^ 



MENDEL not only devised a magnificent method for the 



iSee BATESON, loc. cit., p. 314. QUETELET and MENDEL met the 

 same fate as MARIOTTE, KOELREUTER, CHR. K. SPRENGEL and 

 several other botanists whose fundamental discoveries were overlooked for 

 many years. 



^ This method of investigation is quite independent of MENDEL'S skilful 

 suggestions about dominant or recessive properties and segregation. 



