282 



THE BRYOPHYTES 



the greater part of the chlo- 

 rophyll work (photosynthesis) 

 of the plant, and the chambers 

 are developed as protective 

 structures around them. Each 

 chamber is open above to the 

 air by a circular pore (Fig. 

 247, C), which can be easily 

 seen in the center of each 

 diamond-shaped area. This 

 specialization of the upper sur- 

 face of the Marchantia plant 

 FIG. 248. The cups and buds of 



Marchantia to a light relation gives it a 



A, cup-bearing plant; fi, section of a cup g eneral resemblance to the 



showing the buds arising from its hot- cell Structure of leaves in Seed 



torn ; C, a bud showing the two growing , _, 



points; D, young plant developing from P^ntS ana 



the bud Some individuals of Mar- 



chantia (Fig. 248, A) will usually be found bearing cups (cupules) 

 which contain numerous green bodies. These are many-celled 

 reproductive organs, called 

 buds (gemmae), which de- 

 velop from the bottom of the 

 cup (Fig. 248, B). Each bud 

 has two notches at opposite 

 sides (Fig. 248, C), which 



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become two growing points 

 when the structure falls on 

 its side upon damp earth and 

 begins to grow (Fig. 248,D). 

 This is a characteristic and 

 very successful method of 

 rapid asexual multiplica- 

 tion hi Marchantia. 



The sexual organs of 

 Marchantia are developed 



FIG. 249. The male plant of Marchantia 



A, male plant bearing antheridial receptacles; 

 B, lengthwise section of a receptacle (semi- 

 diagrammatic), showing a row of sunken 

 antheridia upon the upper surface; the 

 youngest lie just back of the notches in the 

 receptacle, which are the growing points; 

 air chambers are also shown on the upper 

 surface 



