410 BOARD OF AGRICULTURE. [Pub. Doc. 



It is a dicotyledonous plant, i.e., it has two cotyledons or 

 seed leaves, Avhich are familiar to all who have observed its 

 germination and development. The cucumber seed is of 

 medium size, and not particular Ij^ well supplied with an 

 over-abundance or great variety of reserve material for in- 

 dependent growth, as shown by its habit of throwing up its 

 cotyledons quite early in its period of development. The 

 cotyledons are withdrawn from the seed coat at an earl}^ 

 period, and as soon as they become exposed to the light they 

 turn gTcen. At this period they commence to assimilate 

 food from the air, through the ability of the green cotyle- 

 dons to decompose the atmospheric carbon-dioxide under 

 the influence of light. 



The principal reserve materials which seeds contain are 

 starch, proteids and oils. All seeds, however, are not sup- 

 plied with these tliree reserve material constituents, but, on 

 the other hand, they may possess only two of these, such as 

 proteids and oils. Such seeds as the pea, horse bean, etc., 

 which contain an abundant supply of the three kinds of 

 reserye material, do not lift their cotyledons into the air, but 

 remain submerged ; Ayhei-eas such plants as the sunflower, 

 white lupine, etc., that contain only proteids and oil (which 

 constitutes a one-sided and incomplete suppl}^ of reserve 

 material), immediately push their cotyledons above ground. 

 The reserye material endowment of this latter class of plants 

 causes them to unfold their cot^dedons and expose them to 

 the light, by which means they are enabled to assimilate food 

 from the air, thus supplying their inherent deficiencies. 



The seed of the cucumber belongs to this latter class, i.e., 

 it contains proteids and oil as a reserve material, but no 

 starch. Hence arises the necessity of utilizing its cotyle- 

 dons as assimilating orgjins at a ver}' early stage in its 

 development, in order that the plant may be supplied with 

 carbohydrate material for metabolism and growth. Fig. 1 

 shows an illustration of the seed of the cucumber and its 

 various parts, together with the seedlings in different stages 

 of development. Usually one end of the seed is thinner 

 and more pointed than the other. The pointed end is where 

 the root protrudes during the process of germination, and 



