24 PHYSIOLOGY. 



bathed with the water. This is known as Marchantia poly- 

 morpha. If we examine the under surface of the marchantia 

 we see numerous hair-like processes which attach the plant to 

 the soil. Under the microscope we see that some of these are 

 similar to the root hairs of the seedlings which we have been 

 studying, and they serve the purpose of absorption. Since, how- 

 ever, there are no roots on the marchantia plant, these hair-like 



Fig. 31. 



Marchantia plant with cupules and gemmae; rhizoids below. 



outgrowths are usually termed here rhizoids. In marchantia they 

 are of two kinds, one kind the simple ones with smooth walls, 

 and the other kind in which the inner surfaces of the walls are 

 roughened by processes which extend inward in the form of irreg- 

 ular tooth-like points. Besides the hairs on the under side of 

 the thallus we note especially near the growing end that there are 

 two rows of leaf-like scales, those at the end of the thallus curv- 

 ing up over the growing end, thus serving to protect the delicate 

 tissues at the growing point. 



