164 



ANCIENT PLANTS 



earliest true Charas date only to the middle of the 

 Mesozoic. 



An interesting occurrence is the petrifaction of masses 

 of these plants together, which indicate the existence of 

 an ancient pool in which they must have grown in abun- 

 dance at one time. A case has been described where 

 masses of Chara are petrified where they seem to have 

 been growing, and in their accumulations had gradually 

 filled up the pond till they had accumulated to a height 

 of 8 feet. 



The plants, however, have little importance from our 

 present point of view. 



Fungi. — Of the higher fungi, namely, "toadstools", 

 we have no true fossils. Some 

 indications of them have been 

 found in amber, but such speci- 

 mens are so unsatisfactory that they 

 can hardly afford much interest. 



The lower fungi, however, and 

 in particular the microscopic and 

 parasitic forms, occur very fre- 

 quently, and are found in the Coal 

 Measure fossils. Penetrating the 

 tissues of the higher plants, their 

 hosts, the parasitic cells are often 

 excellently preserved, and we may 

 see their delicate hyphae wander- 

 ing from cell to cell as in fig. 119, 

 while sometimes there are attached 

 swollen cells which seem to be 

 sporangia. From the Palaeozoic we 

 get leaves with nests of spores of the fungus which had 

 attacked and spotted them as so many do to leaves to- 

 day (see fig. 120). What is specially noticeable about 

 these plants is their similarity to the living forms infest- 

 ing the higher plants of the present day. Already in 

 the Palaeozoic the sharp distinction existed between the 



Fig. 119. — The Hyphae of 

 Fungi Parasitic on a Woody 

 Tree 



c. Cells of host I h, hyphae of 

 fungus, with dividing cell walls. 



