Freeman: Bread Making Wheats for Warm Climates 213 



polishing may be continued until the 

 section has reached the desired thin- 

 ness. In these operations the section 

 is held between the ball of the finger 

 and the grinding surface, light pressure 

 being exerted as the section is moved 

 to and fro. A thin, smooth cloth 

 may be used to protect the linger from 

 abrasion. By this means sections of 

 only a few cells thickness and suffi- 

 ciently transparent for microscopical 

 study, may be prepared without, in 

 any way, disturbing the physical struc- 

 ture of the endosperm. Such sections 

 are best mounted for study directly in 

 balsam, cedar oil, or concentrated gly- 

 cerine. When viewed by transmitted 

 light the horny solid parts of the endo- 

 sperm are clear and transparent, and 

 any air spaces present are made promi- 

 nent as dark objects by the interception 

 of the light. On the other hand, when 

 viewed by reflected light, the air spaces 

 appear as white masses on a dark back- 

 ground. 



APPEARANCE OF GRAINS VARIES 



The comparative appearance of typi- 

 cal sections of a hard and a soft wheat 

 viewed with transmitted light is 

 shown in Fig. 14. In this plate a is 



from a grain of Algerian macaroni 

 wheat, and b is from the Sonora. 

 It should be noted that air spaces are 

 almost entirely absent from the endo- 

 sperm of the macaroni wheat, and are 

 very abundant and diffuse in the So- 

 nora. The crossed seeds were very 

 much wrinkled and exhibited an endo- 

 sperm character intermediate between 

 the parents. The seeds of the Fj plants 

 (Fo endosperm) were also all wrinkled 

 and more or less intermediate between 

 the parents. There was, however, some 

 variation in texture such as may be 

 shown in the series given in Fig. 15. 

 .As is apparent from the plate, the mem- 

 bers of this series grade insensibly into 

 one another so that, whereas one may 

 easily distinguish the extremes, the 

 separation of the seeds into hard, in- 

 termediate and soft groups would be 

 largely arbitrary. Nevertheless such a 

 separation was attempted in the case 

 of two Fj plants, and the seeds planted 

 to test the genetic significance of the 

 separation The results of this test, 

 together with a summary showing the 

 segregation of grain texture in all of 

 the Fg plants arising from the two 

 macaroni bread wheat crosses here de- 

 scribed, are shown in Table I. 



Table I.— Segregation of Grain Texture in the Seeds Borne on the Fi and F^ Plants of Macaroni 



Bread Wheat Crosses 



Intermediate {b) and soft (c) 



(1 X 35 cross Fi plant No. 16-1) 

 (1 X 35 cross Fi plant No. 16-5) 



77% 

 86% 



F2 plants with seeds 



Mixtures of hard (a) 

 All hard (a) intermediate {b) and 

 soft (c) 



All soft (c) 



Selected hard^ seed from 16-1 gave as offspring! 12 



Selected soft ' seed from 16-1 gave as offspring 



Selected hard^ seed from 16-5 gave as offspring 7 



Selected soft^ seed from 16-5 gave as offspring 4 



Unselected seed from 16-1 gave as offspring. . .j 11 



Unselected seed from 16-5 gave as offspring. . . 19 



Total of 1 X 35 cross gave as offspring j 682 



Percentage in each class I 30% 



Total of 1 X 3 cross gave as offspring Ill 



Percentage in each class >^0 % 



^ ^ I 



' Seeds like Plate II, Fig. a. * ggg^g jji^g pi^te II, Fig. 



12 

 14 



7 



13 



36 



39 



1251 



55% 

 227 

 61% 



1 



3 



1 



5 



17- 

 10 

 336 

 15% 

 30 



9% 



Seeds like Plate II, Fig. c. 



