72 



PHYSIOLOG Y. 



169. Frullania. — In fig. 60 is shown another liverwort, 

 which differs greatly in form from the ones we have just been 

 studying in that there is a well-defined axis with 

 lateral leaf-like outgrowths. Such liverworts 

 are called foliose liverworts. Besides these two 

 quite prominent rows of leaves there is a third 

 row of poorly developed leaves on the under 

 surface. Also from the under surface of the axis 



we see here 

 and there 

 slender out- 

 growths, the 

 rh iz o i d s, 

 t h r o u g .h 

 which much 

 of the liquid 



Fig. 62. 



Fig. 60. 

 Portion of plant of 

 Frullania, a foliose 

 liverwort. 



Fig. 61. 

 Portion of same 

 more highly magni- 

 fied, showing over- 

 lapping leaves. 



Under side 



showing forked nutriment IS 



under row of 



leaves and lobes absorbed. 



of lateral leaves. 



170. Nutrition of the mosses. — Among the mosses which 

 are usually common in moist and shaded situations, examples 

 are abundant which are suitable for the study of the organs of 

 absorption. If we take for example a plant of Mnium (M. affine) 

 which is illustrated in fig. 64, we note that it consists of a slender 

 axis with thin flat, green, leaf-like expansions. Examin- 

 ing with the microscope the lower end of the axis, which is 

 attached to the substratum, there are seen numerous brown 

 colored threads more or less branched. (For nutrition of 

 moulds, mushrooms, parasitic fungi, dodder, carnivorous plants, 

 lichens, aquatic plants, etc., see Part III. Ecology.) 



171. The plant body. — In the simpler forms of plant life, as in spirogyra 

 and many of the algse and fungi, the plant body is not differentiated into 

 parts. In many other cases the only differentiation is between the growing 

 part and the fruiting part. In the algae and fungi there is no differentiation 

 into stem and leaf, though there is an approach to it in some of the higher 

 forms. Where this simple plant body is flattened, as in the sea-wrack, or 

 ulva, it is a frond. The Latin word for frond is thallus, and this name is 



