GRASSES OP IOWA. 



89 



Poa trivialis. per cent — 



Poa nemoralls, per cent 



Poa annua, per cent 



Poa compressa, per cent 



Poa pratensis, ppr cent 



Agrostis stolonifera, per cent... 

 Alopecurns praten.si-*. per cent 



CHANGEABLB TEMPERATURB. 



35.33 

 18.0 

 72 17 

 0.0 

 11 72 

 90.34 

 U 5 



62.0 



43 5 



82.33 



18.17 



21.11 



96.0 



46 67 



73.67 

 56 17 

 84 67 

 52.17 

 45.38 

 96 42 

 72.34 



75.33 



57.67 



84.67 



54.5 



49 84 



96.42 



74 43 



Vitality. — When the necessary conditions are present — a fav- 

 orable tempera ure aod moisture — the process begins. The 

 first step is absorption of moisture. When this has proceeded 

 far enough, and with the required amount of heat, the radicle 

 breaks through the coleorhiza or root sheath. The first leaf 

 surrounds the other leaves in the form of a tube, and pushes 

 through the ground; later it opens out. In some cases a single 

 strong primary root appears, but in others a number may even 

 break through the root; sheath. The scutellum remains within 

 the pericarp The young plant is nourished by the material 

 stored away in the endosperm. It is transferred to the embryo 

 by a row of palisade cells that occur on the outside of the scu- 

 tellum. The walls are delicate, and du ing their activity are 

 made up of granular cytoplasm. During the process of germi- 

 nation, the protoplasm does not only become active, but is 

 changed in its structure, as will presently be shown. Now, as 

 a further evidence of germination, it is well known that dur- 

 ing the process, evolution of heat takes place. This is due to 

 oxidation. This process has also been called respiration. The 

 carbohydrates are consumed and CO.^ is given off. This 

 may easily be shown by germinating corn or rye or oats in a 

 close atmosphere in a vessel which does Eot permit the pro- 

 duced gas to escape. This gas may afterwards 

 be collec ed in the well known respiration 

 apparatus of Sachs '. The activity of respira- 

 tion, that is, the carbon dioxide, given off by 

 a given plant, will vary according to the state 

 of development of the seed. At first little 

 will be given off, and as the process of germi- 

 nation increases, more will be given off; as 

 the material is consumed more and more, the 

 process diminishes and the activity of res- 

 piration ceases. 



It has also been shown that plants, during 

 termination, do not lose any nitrogenous 



of wheat, 



