94 COTYLEDONS. 



40. The plumule (Jigs. 121, c, and 125, d] or young stem is 

 sometimes scarcely visible before germination ; at other times it 

 is as long as the radicle with which it is inferiorly continuous : 

 by development it becomes elongated in a direction contrary to 

 that of the root, and consequently it always tends to rise. We 

 distinguish in it two parts, namely : the stemmule and the gemmule, 

 situate one above and the other below the coty'ledons. 



41. The coty'ledons are lateral appendages 

 which represent the first leaves (Jig. 123). They" 

 are almost always thick and fleshy in plants un- 

 provided with albumen, but thin and membranous 

 in endospermntic seeds. Their use seems to be to 

 furnish the young plant with the first alimentary 

 matter, and their number is various ; sometimes 



there is but one and at others there are two or 

 Fig. 123. 



COTYLEDON. , _ ,-,, , , . , , 



42. Plants whose seeds contain only a single 

 coty'ledon, are named monocot.y 'ledons (from the Greek, monos, 

 single, and kotuledbn, seed-lobe) ; those whose seeds contain two 

 or more coty'ledons, are named dicoty 'ledons (from the Greek, dis, 

 two, and kotuleddn, seed-lobe). 



&"- x=*r^\ The annexed figure (124) 



a--"|jglin\ represents the section of a 



seed of a monoeoty'ledon in 

 process of germination, 

 showing the perisperm (a) ; 

 the summit of the single 

 coty'ledon (&) ; the base of 

 the coty'ledon, forming a 

 sort of tube (c) ; at the lower 

 part of the base we see the 

 plumule (d), which sets upon 

 the radicle (e). 



Figure 125 represents the same seed, further Fig. 125. 

 advanced in germination, after the appearance COTYLEDON. 

 of the plumule or young stem (d). 



43. When the seeds are ripe or a short time afterwards, they 

 separate from the plant; sometimes the fruit opens spontaneously 

 to permit their escape ; at other times they are detached without 



Explanation of Fig. 123. A seed in process of germination : c, base of 

 the cotyledon. 



40. What is the plumule ? (Plumule : from the Latin plumula, a little 

 feather.) 



41. What are coty'ledons ? What is their use ? 



42. What is meant by a monoeoty'ledon ? What is dicoty'ledon ? 



43. How are seeds naturally distributed ? 



