OVIPAKA. 201 



Many of tlie cold-blooded Ovipara do not bring forth their young until 

 they are developed and extricated from their shell, or other membranes, 

 which separated them from the mother. These are called /aZse Ovipara. 



' 111 plants we find likewise a placenta or structure, intended for the nourishment 

 and respiration of the foetus. To take the kidney bean for an example, we find 

 within the membranous covering two parenchymatous lobes, or cotyledons; and at 

 the margin betwixt these, there is the corculum or cicatricula. DLiring incubation, 

 we find that this sends up a small shoot called the plumula, and down a radical into 

 the earth. But to support the plant until the root and leaves are capable of main- 

 taining it, we find the cotyledons rise up out of the earth, on each side of the plu- 

 mula, forming what are called seed leaves. These both serve for the respiratory 

 organs, and also supply pabulum, which is absorbed by proper vessels, and in con- 

 sequence thereof they presently are destroyed. When there are more lobes than 

 two in the seed, there are a corresponding number of seed leaves. In many cases 

 these cotyledons do not rise out of the ground, but the plumula alone appears. This 

 is the case with the garden pea, but the cotyledons still perform the functions below 

 the ground, and exist till the foliage of the plant, or adult organs, be formed. The 

 greatest part, then, of a vegetable seed or ovum, consists, like the eggs of fowls, 

 of an apparatus intended for the nutriment and respiration of the foetus, whilst the 

 embryo itself is very small. The cotyledon consists, in many cases, of a fari- 

 naceous substance. In other seeds it is oily and farinaceous, and in some is almost 

 all oily. 



' Vegetable ova sometimes are contained in a dry pericarpium, and are shed into 

 the earth when it bursts. But others have an apparatus provided, not only for their 

 present growth, but also for accelerating their incubation in the earth. In stone 

 fruit and nuts, we find that vessels pierce the shell at the bottom, and pass on toward 

 the top, and reach the kernel or lobes, which are contained within the shell, envelop- 

 ed in a soft membrane. They are inserted very near the embryo. Now, for the 

 farther support of these parts, we find that stone fruits are covered with a quantity 

 of nutritious matter. The almond, for example, has its ligneous nut covered with a 

 substance about an inch thick, enclosed in a proper membrane. The rhamnus lotus 

 has the stone surrounded with farinaceous matter, which tastes like gingerbread. 

 Other seeds are contained in a parenchymatous or succulent substance, as the apple 

 or pear; or in a firm white substance, like cream or man-ow, or in a mucilaginous 

 matter as the gooseberiy, or in an organized pulp as the orange and garcinia man- 

 gostona. Some are deposited in a luscious fluid at first, which ultimately becomes 

 farinaceous, as the plantain.' 



