24- Principles of Plant Culture. 



corn, wheat and many other seeds, the seed-case is of 

 such a nature that it absorbs and transmits water read- 

 ily. In certain seeds, however, as of the honey locust, 

 canna, thornapple, etc., especially if they have been 

 allowed to become dry, the seed-case does not readily 

 transmit water at growing temperatures. Such seeds 

 may lie for weeks, and even months, in tepid water 

 without swelling, but when the water is heated to a 

 certain degree, they swell promptly, a fact often turned 

 to account by nurserymen (36). We cannot always 

 judge by the appearance of a seed-ease whether it will 

 transmit water readily or not. The nature of the seed 

 content and the salts in the soil also influence the rate 

 of absorption of moisture. 



Section II. Germination. 



28. What is Germination? If we place a few viable* 

 grains of Indian corn between the moist cloths of a 

 seed-tester (Fig. 6), cover with the glass and place in a 

 warm room, we shall observe if we examine the corn 

 frequently, that a change, aside from the swelling, will 

 soon take place in at least a part of the grains. The 

 seed-case will be burst by the pressure of a tiny white 

 shoot from beneath. "We say that such grains have 

 sprouted or begun to germinate, i. e., have taken the 

 first visible step toward developing into a plant. 



We have seen that the mature seed contains proto- 

 plasm in a dormant condition (13). At a suitable 

 temperature, the protoplasm, on the absorption of 



of a complex subject, it seems preferable to adopt a term that will 

 include the various words used in botany to designate the outer 

 coAcrings of seeds. 



' A viable (vi'-a-ble) seed is one that is capable of germination. 

 Not all seeds are viable (164). 



