164 



membrane, whose fringed edge constitutes a peristome, which is either 

 single or double, and appears to be the representative of the repro- 

 ductive apparatus ; and the columella is the receptacle, torus or axis 

 on which these several organs are arranged. The calyptra being the 

 analogue of the bractea or involucrum. 



This view is apparently more conformable to the presence of sto- 

 mata on the theca, which have been noticed by Treviranus, Bruch 

 and Schimper, and Valentine, because if the latter organ be really com- 

 posed of leaves, we may therefore, I imagine, more reasonably account 

 for their existence there than by supposing it to be the excavated 

 apex of the stem, such as occurs in an Escholtzia, for the seta is not 

 an organ likely to be furnished with such pores. 



The facts which have been stated, which I believe have not been 

 before described as occurring in a moss, are some of those which, by 

 a little interruption to the ordinary plan of Nature, allow us better to 

 understand some of those plain yet perfect principles of operation, 

 which become more and more evident to us, as we examine the sub- 

 jects of Natural History. 



EXPLANATION OF PART OF PLATE XIX. 



Fig. 5. Plant of Tor tula fallax, in its altered condition, showing the elongated seta 



bearing minute green leaves. 

 Fig. 6. Plant of the same in its natural state. 



