34 2 Mendel's Experiments 



however, a very slight one with Pisum, and is quite 

 incapable of disturbing the general result. Among more 

 than 10,000 plants which were carefully examined there 

 were only a very few cases where an indubitable false 

 impregnation had occurred. Since in the greenhouse such 

 a case was never remarked, it may well be supposed that 

 B ruckus pisi, and possibly also the described abnormalities 

 in the floral structure, were to blame. 



THE FORMS OF THE HYBRIDS*, 



Experiments which in previous years were made with 

 ornamental plants have already afforded evidence that the 

 hybrids, as a rule, are not exactly intermediate between 

 the parental species. With some of the more striking 

 characters, those, for instance, which relate to the form 

 and size of the leaves, the pubescence of the several parts, 

 &c., the intermediate, indeed, is nearly always to be seen ; 

 in other cases, however, one of the two parental characters 

 is so preponderant that it is difficult, or quite impossible, 

 to detect the other in the hybrid. 



This is precisely the case with the Pea hybrids. In 

 the case of each of the seven crosses the hybrid-character 

 resembles f that of one of the parental forms so closely that 

 the other either escapes observation completely or cannot 

 be detected with certainty. This circumstance is of great 

 importance in the determination and classification of the 

 forms under which the offspring of the hybrids appear. 

 Henceforth in this paper those characters which are trans- 

 mitted quite, or almost unchanged in the hybridisation, 

 and therefore in themselves constitute the characters of 

 the hybrid, are termed the dominant, and those which 

 become latent in the process recessive. The expression 

 "recessive" has been chosen because the characters thereby 

 designated withdraw or entirely disappear in the hybrids, 



* [Mendel throughout speaks of his cross-bred Peas as "hybrids," 

 a term which many restrict to the offspring of two distinct species. He, as 

 he explains, held this to be only a question of degree.] 



t [Note that Mendel, with true penetration, avoids speaking of the 

 hybrid-character as "transmitted" by either parent, thus escaping the error 

 pervading the older views of heredity.] 



