EXPEKIMENTS IN PLANT HYBRIDISATION. 



9 



the numerical proportion given without any essential alteration. 

 Transitional forms icere not observed in any experiment. 



Once the hybrids resulting from reciprocal crosses are fully formed, 

 they present no appreciable difference in their subsequent develop 

 ment, and consequently the results |of the reciprocal crosses] can be 

 reckoned together in each experiment. The relative numbers which were 

 obtained for each pair of different characters are as follows : — 



Trial 1. Form of seed. — From 253 hybrids 7,32'4 seeds were obtained 

 n the second trial year. Among them were 5,474 round or roundish 

 ones and 1,850 angular wrinkled ones. Therefrom the relation is 

 deduced of 2-96 to 1. 



Trial 2. Colour of albumen.— 258 plants yielded 8,023 seeds, 6,022 

 yellow, and 2,001 green ; their relation, therefore, is as 3*01 to 1. 



In these two trials each pod yielded usually both kinds of seed. In 

 w^ell-developed pods which contained on the average six to nine seeds, it 

 often occurred that all the seeds were round (Trial 1) or all yellow (Trial 2) ; 

 on the other hand there were never observed more than five angular or 

 five green ones in one pod. It appears to make no difference whether the 

 pods are developed early or later in the hybrid or whether they spring 

 from the main axis or from a lateral one. In some few plants only a few 

 seeds developed in the first formed pods, and these possessed exclusively 

 one of the two characters, but in the subsequently developed pods the 

 normal proportions were maintained nevertheless. 



As in separate pods, so did the distribution of the characters vary in 



separate plants. By way of illustration the first ten individuals from 



both series of trials mav serve. 



Trial 1. Trial 2. 



Form of Seed. Colour of Albumen. 



Plants. 



Round. 



Angular. 



Yellow. 



Green. 



1 



45 



12 



25 



11 



2 



27 



8 



32 



7. 



3 



24 



7 



14 



5 



4 



19 



10 



70 



27 



5 



32 



11 



24 



13 



6 



26 



6 



20 



6 



7 



88 



24 



32 



13 



8 



22 



10 



44 



9 



9 



28 



6 



60 



14 



10 



25 



7 



44 



18 



As extremes in the distribution of the two seed characters in one 

 plant, there were observed in Trial 1 an instance of 43 round and only 

 2 angular, and another of 14 round and 15 angular seeds. In Trial 2 

 there was a case of 32 yellow and only 1 green seed, but also one of 

 20 yellow and 19 green. 



These two trials are important for the determination of the average 

 relative figures, because with a smaller number of trial plants they show- 

 that very considerable fluctuations may occur. In counting the seeds, 

 also, especially in Trial 2, some care is requisite, since in some of the seeds 

 of many plants the green colour of the albumen is less developed, and at 

 first may be easily overlooked. The cause of the partial disappearance of 



