AND THE STRUCTURE OP PLANTS. 



81 



egg of the plant is its seed : a doctrine not of modern origin, but taught 

 and understood quite as clearly, and with as close a reference to the rise 

 of animal life, by the ancients, as in the present day.* The seed is some- 

 times naked, but more generally covered with a pericarp, whence plants 

 become naturally divided into the two grand arragements of gymnosper- 

 mous, and angiospermous. The pericarp is of various forms and struc- 

 tures ; and of these the more common are the legume, silique, or silicle, 

 being merely varieties of what, among ourselves, is denominated in popu- 

 lar language cod or pod ; the loment, which is a kind of pod not so fre- 

 quent as either of the former, but of which we have an instance in the mi- 

 mosas and the cassia Fistula ; the pome or core-apple, of which we have 

 instances in the common apple and the pear ; the drupe, or stone-apple, 

 instances of which occur to us in the plum, cherry, and almond ; the glume 

 or chaff ; the berry ; the acinus or conglomerate berry, as in the rasp ; the 

 nut ; and the capsule.j 



Stripping olf this outer covering, we find the seed to consist internally of 

 a corculum^ or heartlet, and externally of a fleshy or parenchymatous sub- 

 stance, surrounded with a double integument, sometimes single, sometimes 

 bifid, and sometimes more than bifid ; and hence denominated monocoty- 

 ledonous, dicotyledonous, polycotyledonous. In popular language these 

 are called seed-lobes, or seed-leaves : and in the phaseolus vulgaris^ or 

 common kidney-bean, we have as striking an instance as in any plant, and 

 which every one must have noticed, just peeping in two distinct segments 

 above the ground, as soon as the seed has begun to germinate. It was 

 very generally supposed formerly, and is still supposed by some botanists, 

 that the seeds of various orders of plants, as the mosses, fungi, and algae, 

 are acotyledonous, or totally destitute of a cotyledon of any kind. But as 

 many, perhaps most, plants of this kind have of late been found to possess 

 some such parenchyma, we have great reason for believing that thi^ organ 

 is universal, and'that there is no such thing as an acotyledonous seed in the 

 whole vegetable kingdom. In reality, the cotyledon appears absolutely 

 necessary for the germination and future growth of the seed, and may hence 

 be denominated its lungs or placentule. Like the perfect plant, it pos- 

 sesses lymphatics and air vessels. Through the former of these it absorbs 

 the moisture of the soil into which it is plunged, decomposes a part of it 

 into its elementary principles, and conducts those principles, together with 

 the undecomposed water, to the corcle or heartlet, which becomes stimu- 

 lated to the process of germination by the oxygene thus set at liberty. 



Mrs. Ibbetson has attempted to prove that the cotyledon is of no use . 

 whatever for the purpose of nourishment ; which, according to her observa- 

 tions, is only conveyed to the corcle by what she calls a system of nourish- 

 ing vessels, altogether distinct from the cotyledon. It is not very clear, 

 however, what is here meant, by nourishing vessels ; nor can we for a mo= 

 ment admit that so large an organ as the cotyledon, and apparently so im= 



portant, can be designed for no other office, than merely, as this lady con- 



( 



* 'OvTW ^' ^woTOKEi ixiKpa SevSpca Trpoyrov eXatag 



Empedocles, 



So plants, like animals, uprise to air, 

 And in green eggs young olives olives bear. 

 And upon this beautiful verse, which he has preserved as a fragment, Aristotle remarks., 

 ■ TO Tt yap MOV Kvrjpa sarif Kai ek nvog avrov yiyvsraiv to ^(oov. "For the egg is the conception, 

 and after the same manner the animal is created." De Generat. Animal, i. 23. 



t Compare Knight's general theory of vegetable physiology, Horticultural Transactions?;, 

 Tol. i. p, 217. with Nicholson's Journal, vol. xxxii. p. 350, 



