144 



BOTANY. 



238. Sporogonium of liverworts. If the sporogonium 

 (spore-case) of marchantia cannot be obtained those of any 

 other liverwort may be used. 



239. Sporogonium of marchantia. If 



we examine the plant shown in fig. 124 

 we shall see oval bodies which stand out 

 between the rays of the female receptacle, 

 supported on short stalks. These are the 

 sporogonia, or spore-cases. We can see 

 that some of the spore-cases have opened, 

 the wall splitting down from the apex 

 in several lines. This is caused by the 

 drying of the wall. These toothlike 

 divisions of the wall now curl backward, 

 and we can see the yellowish mass of the 

 spores in slow motion, falling here and 

 there. It appears also as if there were 

 twisting threads which aided the spores 

 Fi I2 in becoming freed from the capsule. 



Marchantia poiymorpha, 240. Spores and elaters. If we take 



archegomum with egg; /, 



curtain which hangs down a bit of this mass of spores and mount 



around the archegonia; *, 



egg; v, venter of archego- it in water for examination with the 



nium ; , neck of archego- 



nium. microscope, we shall see that, besides 



the spores, there are very peculiar thread-like bodies, the mark- 

 ings of which remind one of a twisted rope. These are very 

 long cells from the inner part of the spore-case, and their 

 walls are marked by spiral thickenings. This causes them in 

 drying, and also when they absorb moisture, to twist and curl 

 in all sorts of ways. They thus aid in pushing the spores out 

 of the capsule as it is drying. 



241. How marchantia multiplies. New plants of mar- 

 chantia are formed by the germination of the spores, and 

 growth of the same to the thallus. The plants may also be 

 multiplied by parts of the old ones breaking away by the action 

 of strong currents of water, and when they lodge in suitable 



