VEGETABLE PHYSIOLOGY. 47 



often protruded to the lower side of the branches, where they 

 grow. Some people are persuaded, that the sessile and flat 

 fungi on trees, are morbid excrecencies ; but it is obvious 

 they are true species of those agarics which are furnished with 

 caps and stems, and grow on the ground, whose seeds falling on 

 a moist tree, produce, as it were, half cups without stems. 



That seeds are the eggs of plants, appears from hence, that 

 as every egg produces an. offspring similar to the parent, so do 

 the seeds of vegetables, and consequently they also are eggs. 

 The containing parts of a hen's egg are, the shell, the external 

 film or membrane, the internal membrane lying immediately 

 under the former, the chalazce, or membrane inclosing the yolk, 

 twisted at the extremities. The parts contained are, the air 

 within the membranes at the obtuse end of the egg, the albumen, 

 or w T hite, the vitellus, or yolk, in the centre the punctum vitce, or 

 point of life. When a perfect egg is placed under a hen, after 

 two days' incubation, the speck of life becomes red, sends out 

 its blood vessels through the yolk, and at last we find the whole 

 chick is formed out*of the speck of life. The yolk becomes the 

 secondines ; the white contributes to the nourishment of the 

 chick ; and the two membranes become the amnion and chorion. 

 Every seed of a vegetable, as we have before shown, is in struc- 

 ture essentially the same as the egg of a bird, endowed with ves- 

 sels, and contains under several membranes, the plant in miniature. 

 When a seed is exposed to a due portion of moisture, and a just 

 degree of heat, it begins to swell, and on its out side, there is 

 seen a vesicle, which is the amnion of Malpighi, furnished with 

 an umbilical cord, which is produced through the chorion to the 

 opposite side of the egg. While with the egg the amnion in- 

 creases, on its top is observed another small body, which like- 

 wise augments continually, till it has filled the whole chorion of 

 the egg ; and the amnion and chorion are turned into the exter- 

 nal shell or coat of the seed. That most plants have seminal 

 leaves or lobes is very well known. Now these seminal leaves 

 once constituted the whole seed, except the hilum, or little 

 heart, in which is the point of life ; and these lobes prepare the 

 nourishment for the tender plant, until it be able to strike root in 



