36 
eee and stored by the plant for its own use and that of 
mbryos and seedlings it produces and it is a commonplace 
a evolutionary theory that the highly specialized animals with 
their strongly developed muscular and nervous systems would 
not be possible except for the concentrated food stuffs of the 
plant seed. A prerequisite for the evolution of the highly per- 
fected animal types of the present day was the development of 
the seed habit in plants with its concomitant forehanded storage 
of concentrated foods intended for the seedling but which can 
be diverted to the use of the predatory animal. ee seeds 
were available as foods he Diveroue animals were dependent 
largely on what h roughage, demanding 
Ree developed digestive tracts at Hane capacity. 
Looked at from the standpoint of economics, the work of the 
farmer is to a large degree the production of carbohydrates by 
the use of the plant mechanism. Carbohydrate formation is 
known as light assimilation, or photosynthesis. The organs of 
light assimilation are the green leaves. The raw materials for 
carbohydrate synthesis are carbonic acid gas from the air an 
water largely from the soil. The energy necessary to bring about 
the chemical synthesis is furnished by sunlight. It is of interest 
that the supply of raw materials for carbohydrate formation and 
the necessary energy available in the form of sunlight are both 
practically inexhaustible and the farmer need not concern 
himself with problems of the conservation of raw materials or 
energy in this immediate connection. 
The chemistry of the synthetic process has been one of the 
most constantly studied problems in the whole domain of plant 
physiology, and there is still no agreement as to the fundamental 
processes involved. Two widely divergent views have been held. 
According to the one, starch is a dissociation product of more 
complex nitrogenous compounds which are first formed. Ac- 
cording to the other view, the carbonic acid gas and water are 
more directly built up into sugars and then starch. Even the 
under standard conditions of temperature, light, carbonic acid 
gas supply, etc., has never been adequately determined, but it is 
