CHARACTERS COMMON TO DICOTYLEDONS. 59 



Schedules descriptive of the Maple should be filled up, 

 taking that of Willow as the model. 



CHAPTEE XL 



CHARACTERISTICS POSSESSED IN COMMON BY ALL THE PLANTS 



PREVIOUSLY EXAMINED STRUCTURE OF THE SEED 



IN DICOTYLEDONS. 



78. Before proceeding further in our examination of 

 plants, we shall direct your attention to some characters 

 of those already examined, which they all possess in 

 common. The leaves of every one of them are net-veined. 

 Some leaves, at least, of each of them have distinct petioles 

 and hlades. The parts of the flowers we found, as a gen- 

 eral thing, to be in fives. In one or two instances they 

 were in fours, that is four sepals, four petals, and so on. 

 79. Now, in addition to these resem- 

 blances, there are others which do not 

 so immediately strike the eye, but which, 

 nevertheless, are just as constant. One 

 of these is to be found in the structure 

 Fig. 77. Fig. 78. Fig. 79. of the embryo. Take a Cucumber or a 

 Pumpkin seed, and having soaked it for some time in 

 water, remove the outer coat. The body of the seed will 

 then readily split in two, except where the parts are joined 

 at one end (Figs. 77, 78, 79). The thick lobes are called 

 cotyledons, or seed-leaves, and as there are two, the embryo 

 is dicotyledonous. The pointed end where the cotyledons 



Figs. 77, 78, 79. Different views of Pumpkin seed, showing radicle, 

 cotyledons, and plumule. 



