80 MORPHOLOGICAL DEVELOPMENT. 



duction of branch out of branch, shows us this integration 

 repeated over and over again ; forming an aggregate having a 

 degree of composition too complex to be any longer defined. 



[NOTE. A criticism passed on the general argument set 

 forth in the foregoing sections, runs as follows : " I have 

 already pointed out that the process of evolution by which 

 you believe the Liverworts with a distinct axis and append- 

 ages to have been produced from the thalloid forms is not 

 founded on sound evidence either in comparative morphology 

 or development. But even if we admit that such an inte- 

 gration of a proliferously-produced colony might have given 

 rise to the leafy Jungermanniacece, there are even more 

 weighty objections to the supposition that the same process 

 produced the shoot structures of the flowering plants. In the 

 first place the flowering plant-body is not homologous with 

 the liverwort plant-body, since they represent different genera- 

 tions. The liverwort plant-body or gametophyte, i.e., the 

 generation bearing sexual organs, is homologous with the 

 prothallus of ferns and other Pteridophytes, and in the 

 Flowering Plants with reduced structures contained within 

 the spores (embryo-sac and pollen-grain) but still giving rise 

 to sexual cells. The liverwort spore-capsule and its accessory 

 parts (in fact everything produced from the fertilized egg) is 

 homologous with the sporogonium of the mosses, and, as most 

 botanists think, with the leafy plant-body of Pteridophytes 

 and Phanerogams. This generation is called the sporophyte 

 and from the spores which it produces are developed the 

 gametophytes of the next generation. These generalizations 

 were first established by Hofmeister, and all subsequent 

 work has tended to establish them more firmly. The 

 only doubtful question is (and the doubt is mainly, I think, 

 peculiar to myself, certainly not being shared by the majority 

 of botanists) whether the sporophyte of Mosses and Liver- 

 forts is really homologous with that of Pteridophytes and 



