EUROPE AND NORTH AMERICA. 



'5 



ventricosfi at base, and gradually contracted upward into a more 

 or less d ;inct, somewhat arched neck, which is perforated by a 

 foramen at apex ; they are very distinct in Sphagnum tencllum, 

 but in some species the neck is scarcely evident ; one of these 

 retort cells always falls at a leaf insertion, and they never contain 

 spiral threads, even when these are present in the ordinary cells 

 of the branch cuticle. 



In most species of Sphagnum the branches which constitute 

 each fascicle are of two forms ; part of them stouter and directed 

 outwards from their insertion, become arched at the middle ard 

 gently curve downward at the extremity, and these may be called 

 the divergent branches ; the rest are longer and more attenuated, 

 with longer and narrower leaves, hang straight down, and are 

 often closely appressed to the stem ; these we term the pendent 

 branches, and the number and direction of each of these in a 

 fascicle is pretty constant in each species. 



The branches always stand close to a leaf, at the end of its 

 line of insertion on the stem, and at every fourth leaf a branch 

 fascicle is found, their arrangement being in five straight rows, with 

 the formula \, i. e. three complete turns of a spiral contain five 

 fascicles. 



Some of the uppermost divergent branches become condensed 

 and clavate, and form the amenti.la of male inflorescence. 



It is by means of the pendent branches and cuticle of the stem 

 that the wonderful hydraulic property of the Sphagna is main- 

 tained, and this is readily seen if we place an uninjured stem in a 

 glass of water and allow the top to hang over the margin, for the 

 water rises by this channel, and soon begins to drip from the 

 drooping end, until, like a syphon, it has drawn off all the contents. 

 Not only do the Sphagna thus give off water to the atmosphere, 

 but they can on the other hand also absorb moisture from it and 

 transmit it downward ; in this way a constant interchange goes on 

 between the stagnant pools and the atmosphere, by which means 

 no doubt the former are prevented from becoming putrid. 



The Leaves. 



Hofmeister admirably describes the development of the leaves 

 of Sphagnum ; they arise from the outer cell layer of the growing 

 point, the first leaf cell appearing from the second, third, or fourth 

 cell below the terminal one, and this dividing repeatedly by alter- 



