GERMINATION". 313 



For all agricultural plants cultivated in New England, 

 a range of temperature of from 55 to 90 is adapted for 

 healthy and speedy germination. 



It will be noticed in the above Table that the seeds of 

 plants introduced into northern latitudes from tropical re- 

 gions, as the squash, bean, and maize, require and endure 

 higher temperatures than those native to temperate lati- 

 tudes, like wheat and barley. The extremes given 

 above are by no means so wide as would be found were 

 we to experiment with other plants. It is probable that 

 some seeds will germinate nearly at 32, or the freezing 

 point of water, while the cocoa-nut is said to yield seed- 

 lings with greatest certainty when the heat of the soil is 

 120. 



Sachs has observed that the temperature at which 

 germination takes place materially influences the relative 

 development of the parts, and thus the form of the seed- 

 ling. According to this industrious experimenter, very 

 low temperatures retard the production of new rootlets, 

 buds, and leaves. The rootlets which are rudimentary in 

 the embryo become, however, very long. On the other 

 hand, very high temperatures cause the rapid formation 

 of new roots and leaves, even before those existing in the 

 germ are fully unfolded. The medium and most favora- 

 ble temperatures bring tfie parts of the embryo first into 

 development, at the same time the rudiments of new or- 

 gans are formed which are afterward to unfold. 



>. Moisture* A certain amount of moisture is indis- 

 pensable to all growth. In germination it is needful that 

 14 



