72 



The Journal of Heredity 



THIRD GENERATION FROM SEMI -STERILE PARENT 



The opposite cut showed the product of fertile F2 plants; this one shows the product of semi- 

 sterile F2 plants, in the same cross, Philippine Lyon by Florida Velvet. The plants 

 which bore the above pods are first-cousins of the ones which bore the pods on the 

 preceding page. These were all the product of one semi-sterile F2 plant, which wa'= in itself 

 the product of the usual semi-sterile Fl plant. As is evident, half of these plants bore 

 pods, represented by the three at the left, which contain the full complement of beans; 

 the other half of the plants produced pods typified by the three at the right, which arc 

 again semi-sterile, and contain only half as many seeds as they would have, if all their 

 ovules were properly developed. The first three of these plants had normal pollen; the 

 second three had semi-sterile pollen. (Fig. 10). 



the progeny of seven semi-sterile plants 

 consisted of 106 fertile plants and 102 

 plants with semi-sterility of pollen and 

 ovules. 



Fig. 9 is a photograph of jiods of 

 six third-generation plants. These be- 

 longed to the family of one fertile 

 second-generation ]jlant. All had nor- 

 mal ]Jollen. They descended from the 

 Lyon by Velvet cross. 



Fig. 10 (to be compared with Fig. 9) 

 gives the pods from six third-generation 

 plants (first cousins to those in Fig. 9). 

 These belonged to the family of one 

 semi-sterile second-generation ])lant. 

 The first three had normal jjollen, the 

 last three had semi-sterile jioUen. 



FOURTH AND FIFTH GENERATIONS 



No semi-sterile plants have been 

 tested beyond the third generation, but 

 fertile ]:)lants remain fertile in pollen and 

 ovules in F4 and F5. Several acres of 

 those fertile plants which are of agri- 

 cultural value have been grown in F5, 

 and many flowers and ])ods examined, 

 all of which were fertile. 



In this investigation the pollen of 

 over 2600 flowers has been examined 

 under the microscoj^e, and about 2300 

 yoimg pods and 3700 dry pods have 

 been o]3ened, and the seeds and aborted 

 ovules counted. In 1910, two acres 

 of ])lants were grown; in 1911, the 



