November, 1907 



AMERICAN HOMES AND GARDENS 



431 



The Birth of the Wheat 



By Percy Collins 



[GRAIN of wheat! Probably no single ob- 

 ject, great or small, possesses a fuller sig- 

 nificance, or is pregnant with a wider possi- 

 bility in its relation to mankind than this 

 tiny seed, which measures, in its dry state, 

 one-quarter of an inch in extreme length. 

 Think, for a moment, what would happen 

 if this grain, with its fellows throughout the world, were by 

 some unforeseen chance to chain up its life principle within 

 itself — if, in other words, germination were to be arrested for 

 a single year. The result to mankind would be appalling. 

 Not only would myriads of our fellow creatures be brought 

 to the verge of starvation, but the whole fabric of civilization 

 would be shaken to its foundations. 



By what means is this calamity averted year by year? In 

 what manner is the birth of the wheat secured? Man takes 

 but small part in the miracle. True, he prepares the soil and 

 watches long and patiently for the harvest. But with the 

 actual labor of birth he has no concern. Nature alone holds 

 the key, and we can only stand and marvel as we see the door 

 of life revolving upon its hinges. 



If we examine a grain of wheat (Fig. i) separated from 

 an ordinary farmer's sample, we see that it is more or less 

 spindle-shaped, with a groove or channel on one side and a 

 tuft of silvery hairs at one extremity. But the grain is 

 shrunken, and its skin is wrinkled, and we shall be able to 

 examine it more profitably after it has been steeped in water 

 for, say, a period of twelve hours. Moisture will now have 

 passed into the 

 grain, and it will 

 have become swol- 

 len — completely fill- 

 ing the envelope, or 

 skin, which pro- 

 tected it during its 

 period of sleep, 

 which is now draw- 

 ing to a close. 



Regarding first 

 what we may term 

 the obverse of the 

 grain (Fig. 2) we 

 notice again the tuft 

 of silvery hairs at 

 one extremity, 

 and at the other a 

 slight prominence, 

 bounded by a de- 

 pressed area, or 

 ditch. This promi- 

 nence will shortly 

 call for our undi- 

 vided attention. It 

 is the embryo — the 

 germinating point 

 of the seed — -the 

 spot whence issues 

 the living wheat 

 plant. For the mo- 

 ment, however, it 

 will be sufficient to 

 note that one ex- 

 t r e m i t y of the 



1 — The Untouched Grain 



2 — The Grain Soaked in Water : Obverse 



3 — The Same Reversed 



4 — The Beginning of Growth 



5 — ^The Protrudance of the Sheath Guarding 



the Primary Root 



prominence — that nearest to the hairy end of the grain — is 

 termed, because of what lies beneath it, the plumule, or 

 young shoot. The other extremity, for a like reason, is 

 known as the radicle, or young root. 



We may now turn the grain over and examine its reverse 

 (Fig. 3). The tuft of hairs is still a feature, and we notice 

 that the groove, or channel, originates among them. It may 

 be regarded, in fact, as a kind of irrigation channel; for it 

 provides a passage for the moisture collected by the hairs, 

 and carries it to the embryo, the radicle of which is seen 

 protruding from beneath. By means of the tuft of hairs, the 

 groove, and the depression which surrounds the embryo upon 

 the obverse, side of the grain, the young root and the young 

 shoot are constantly anointed with moisture throughout the 

 whole period of their early development. 



It is important to bear in mind that the bulk of the seed 

 in a grain of wheat consists of a store of nourishment 

 destined to support the young plant during the period of 

 germination, and until it is sufficiently established to obtain 

 food for itself from the surrounding elements. This store 

 is called the albumen, and is quite distinct from the embryo, 

 with its plumule and radicle, which forms the prominence at 

 one end of the grain. The albumen, in fact, closely resembles 

 the yolk-bag which is attached to and nourishes the young 

 chicken prior to its escape from the egg shell. 



The conditions necessary for the germination of a grain 

 of wheat are moisture, warmth and the presence of oxygen. 

 Exposed to these influences, the pent-up life within the grain 



begins to manifest 

 itself. The skin 

 above the embryo 

 ruptures, forming 

 first a tiny orifice, 

 which rapidly 

 lengthens until a slit 

 extending from end 

 to end of the prom- 

 inence is formed 

 (_F I g . 4). The 

 birth of the wheat 

 has now fairly com- 

 menced. 



Later — after an 

 interval, perhaps, 

 of several hours — 

 the watcher ob- 

 serves the sheath 

 which guards the 

 primary root pro- 

 truding (Fig. 5). 

 A few hours more 

 and the whole 

 sheath will be ex- 

 posed to view ; the 

 protecting skin will 

 be forced aside; 

 while the tips of the 

 young root and the 

 young shoot will 

 have emerged from 

 opposite ends of the 

 sheath ( Fig. 6) . 

 At this period It Is 



6 — The Tips of the Young Root and the Young Shoot 



Have Emerged from Opposite Ends of the Sheath 



7 — The Extension of the Primary Root 



8 — The Development of the Adventitious Roots and 



the Root -hairs 



9 — The Beginning of a Second Pair of Adventitious Roots 



