68 



ANCIENT PLANTS 



though as regards size and output of spores there was 

 a considerable difference in favour of the fossils. The 

 plan of each is that round the axis of the cone simple 

 scales are arranged, on each of which, on its upper side, 

 is seated a large sporangium bearing numerous spores 

 all of one kind (see fig. 46). 



Equally similar are the cones of the living Equisetum 

 and some of the simple members of the fossil family 



Calamiteae, but the more in- 

 teresting cases are those where 

 differences of an important 

 morphological nature are to 

 be seen. 



As regards the second ^ 

 generation there is some very 

 important evidence, from ex- 

 tremely young stages, which 

 has recently been given to the 

 world. In a fern sporangium 

 germinating spores were fossil- 

 ized so as to show the first 

 divisions of the spore cell. 

 These seem to be identical 

 with the first divisions of some recent ferns (see fig. 47). 

 This is not only of interest as showing the close simi- 

 larity in detail between plants of such widely different 

 ages, but is a remarkable case of delicate preservation 

 of soft and most perishable structures . in the " coal 

 balls ". 



While these few cases illustrate points of likeness 

 between the fructifications of the Coal Measures and of 

 to-day, the large size and successful character of the 

 primitive Coal Measure plants was accompanied by many 

 developments on the part of their reproductive organs 

 which are no longer seen in living forms, and the greater 



iThe gametophyte generation (represented in the ferns by the prothallium on 

 which the sexual organs develop) alternates with the large, leafy sporophyte. Refer 

 to Scott's volume on Flowerless Plants (see Appendix) for an account of this 

 alternation of generations. 



Fig. 47. — Germinating Fern Spores 



A and B, from carboniferous fossils; 

 c, living fern, (a and B after Scott.) 



