30 BRITISH MOSSES. 



truth, the professor himself admits. The evidence of the 

 Mosses seems to amount at least to this : that in this whole 

 group, the highest in this line of development, where the 

 oophytic generation produces the principal plant, and where 

 there are highly specialized organs for the production of 

 spores or germ cells that in this whole group either there 

 is no effectual separation between the two kinds of plasma, 

 or that the germ plasma is so widely diffused amongst the 

 somatic plasma that every portion of the plant is capable 

 of reproducing the entire organism. 



Comparison with Zoological Embryology. The table will 

 further offer us some points of comparison with animal 

 embryology. 



In that branch of physiology, one of the most remarkable 

 facts is what has been called recapitulation, i.e., the sum- 

 mary in the life of the individual of the life of the race, so 

 that the development of the individual tells the development 

 of the race e.g., the gills of the tadpole tell us of the 

 descent of the Batrachians from gill-breathing animals. 



So here we cannot doubt that the protonema of the 

 Moss tells us of the descent of the whole group of Mosses 

 from the Algse. 



Another remarkable fact in animal embryology is the 

 co-existence in exceptional cases of the mature and the 

 immature form : so the axolotl retains both gills and lungs 

 throughout its life. In like manner some Mosses retain 

 their algoid protonema throughout life. 



The Phascum or Clay Moss is a conspicuous instance of 

 this curious fact : it is depicted in Fig. 17. It is a Moss of 

 a not very high organization. The leaves grow close to the 



