THE TIKST-TIDE POOL. 43 



Ovate capsules or cells, containing pear-like spores. 

 2. Tetraspores, or clusters of four spores, imbedded in 

 swollen brandies. 



Polysiphokia Pastigiata (Tufted Polysiphoma) . 

 — This is the first we shall meet with, and never appre- 

 ciate unless we have a microscope, for it simply dries 

 black and occupies a careless corner of the album, 

 passed over as a weed and nothing more, of no great 

 importance either. I would therefore beg of you to 

 take a small piece of any you see in fruit, that is, with 

 swollen tips, and place it on a glass slide, with a drop 

 of water, covering it with a bit of thin glass. I repeat 

 this, because if the weed be laid on dry and loose, we 

 see nothing; the water renders it transparent, and the 

 pressure of the glass exhibits the structure of the 

 substance. 



~We see now the rows of tubes or siphons which 

 give the name to the plant ; short rows of about six- 

 teen tubes : the joints are short, and in the centre of 

 each is a sac, or cell, of coloured matter, which makes 

 a dark spot, and will help to distinguish it from other 

 species. The swollen tips will show an urn-like cell, 

 supported by a short horn at its side ; the texture of 

 the cell is transparent, and on slight pressure the 

 pear-shaped spores will probably come out. If we 

 take a neighbouring plant, the tetraspores will be 

 found embedded in smaller branches near the fork, 

 and irregularly placed. In winter a new kind of 

 fructification appears — yellow oblong bodies abound 

 at the tips of the ramuli, and give the whole plant a 

 yellow hue. This is not thoroughly understood. 



