AMONGST THE SEAWEEDS. 19 



lichens, fungi, mosses, and ferns. What we are 

 concerned with, then, are marine algae, plants that 

 have no vascular tissue, nor any root, stem, leaves, 

 flowers, nor seeds. There are seaweeds which seem 

 to possess roots, but these are mere sucker-like discs, 

 and have no root-functions in regard to nutrition, 

 while the so-called stems and leaves are, accurately 

 speaking, fronds and their modifications. Those 

 curious vesicles on so many marine algse, which 

 look like pods or seed-vessels, and which the novice 

 might suppose were concerned in reproduction, are 

 in reality nothing but air-vessels, whose function is 

 to keep the fronds floating. The higher algae are 

 reproduced by spores, and others by zoospores. The 

 former method is analogous to that which obtains 

 amongst ferns, while zoospores are cells that separate 

 from the parent plant. In general, when repro- 

 duction is by spores, there are organs which in some 

 senses correspond to the anthers and pistils of 

 flowers. In the spore cavity or conceptacle, are 

 certain bodies called antheridia, which fertilize the 

 spores proper. Many of the green seaweeds are 

 reproduced by zoospores, which method has been 

 thus described by Dr. Harvey, the well-known 

 phycologist : " In an early stage the green matter, 

 or endochrome, contained within the cells of these 

 algse is of a nearly homogeneous consistence through- 

 out, and nearly fluid ; but at an advanced period it 

 becomes more and more granulated. The granules, 

 when formed in the cells, at first adhere to the 

 inner surface of the membranous wall, but soon 

 detach themselves, and float freely in the cell. At 



