SEEDLINGS. 11 



stem, or Oaulicle, breaks through the coverings of the seed, 

 and grows downward to form the root. In case of some spe- 

 cies but one root develops directly from the seed. In others 

 two or more appear almost simultaneously ; these are really 

 branches from the caulicle. When the development of the 

 embryo is so far advanced that the testa (covering) of the 

 seed is thrown off, or that the stem appears above ground, 

 many peculiarities present themselves. For the investigation 

 of these the germinator if properly managed will furnish 

 ample material. 



3. It will be seen that in many cases there are two seed- 

 leaves (for example, the two halves into which a pea or bean 

 splits) called Cotyledons. All plants having two cotyledons 

 belong to the group called Dicotyls. In these, great varia- 

 tion is seen in the form of the seed-leaves ; some are narrow, 

 others are broad ; in a few cases they are unequal ; some are 

 sessile — i. e. without a stem to the blade or broad part; others 

 are on long petioles (leaf-stems). They generally have an en- 

 tire margin, but some are scalloped or lobed, or they may be 

 notched at the apex or even two-cleft or three-cleft. Some 

 cotyledons are lifted above the surface of the soil by the 

 lengthening of the caulicle, expand more or less and become 

 green so that they strongly resemble ordinary foliage leaves. 

 In other cases they do not increase in size, but remain within 

 the seed-covering underground; they do not then become 

 green, nor have any resemblance to leaves, and they soon 

 disappear. 



The seedlings from the germinator will show these variations if they 

 are studied at the proper time. They should be examined and sketched in 

 detail, by each pupil before a recitation is called for, or before the text is 

 studied. This will require many hours' work and should form several les- 

 sons. The specimens should be saved, when possible, for subsequent refer- 

 ence. The pupil should also collect for illustration seedlings from the 

 woods, fields, etc., during the growing season. Such specimens can be dried 

 between folds of paper under pressure, and then glued to sheets of card- 

 board, or thick white paper, of uniform size — eight and one-quarter by eleven 

 and one-half inches (this being just half the size of standard sheets for botan- 

 ical specimens). 



