GREGOR MENDEL 



once; thus the IVth case should occur four times as frequently as the 1st and 

 twice as frequently as the Ilnd or Illrd. 



If on the other hand, plants grown from the round yellow seeds mentioned 

 are fertilized by pollen from green angular plants, the results should be exactly 

 the same, provided that the ovules are of the same types, and formed in the 

 same proportions, as was reported for the pollen. 



I have not performed this experiment myself, but I believe, on the basis of 

 similar experiments, that one can depend on the result indicated. 



In the same fashion individual experiments may be performed for each of 

 the two seed characters separately, all those round seeds which occurred to- 

 gether with angular ones, and all the yellow ones which occurred with green 

 seeds on the same plant are suitable. If, for instance, a plant with green seeds 

 was fertilized by one with yellow seeds, the seeds obtained should be either 

 1) all yellow, or 2) half yellow and half green, since the plants originating 

 from yellow seeds are of the varieties B and Bb. Since, furthermore, B and Bb 

 occur in the ratio of 1:2, the 2nd fertilization will occur twice as frequently 

 as the 1st. 



Regarding the other characters, the experiments may be conducted in the 

 same way; results, however, will not be obtained until next year. . . . 



As must be expected, the experiments proceed slowly. At first beginning, 

 some patience is required, but later, when several experiments are progressing 

 concurrently, matters are improved. Every day, from spring to fall, one's in- 

 terest is refreshed daily, and the care which must be given to one's wards is 

 thus amply repaid. In addition, if I should, by my experiments, succeed in 

 hastening the solution of these problems, I should be doubly happy. 



Accept, highly esteemed Sir, the expression of most sincere respect from 



Your devoted, 

 G. Mendel 



(Altbriinn, Monastery of St. Thomas) 

 Briinn, 18 April, 1867 



s-14 



