1 88 



OUTLINES OF PLANT LIFE. 



263. 



II. Spores. 

 Sexual and non-sexual spores. — A spore is a single- 

 celled body capable of producing 

 a new plant. Spores may be 

 formed either by a process of 

 growth or by the union of two 

 cells. The former are called non- 

 sexual spores; the latter, sexual 

 spores. Only non-sexual spores 

 are discussed in this chapter. 



264. Motile spores. — Spores 

 may be either naked and motile 

 or furnished with a cell-membrane 

 and non-motile. The former are 

 commonly produced by plants 

 which pass all or part of their lives 

 in water, such as the algae and 

 aquatic fungi. They are usually 

 pear-shaped and furnished with one 

 or more cilia, by means of which 

 they swim about (figs. 109, 140). 

 When locomotion was supposed 

 to be a distinctive power of ani- 

 mal bodies they were called zoo- 

 spores, a name still retained. They 

 F.G..4o.-i>eve'opment and escape ^re also Called swarm-spores. 

 (l53"S«lT/.TThe"elS Zoospores are formed either in 



of two hyphae are shown, the ter- 



yph 



minal cells being spore cases. In 



f.;,™\P'°'T'*',?i '" ^"'.^?"f 1°, different 



general body-cell, not visibly 

 form spores. From -■<> many of "'^^'erent from the Other body- 

 Srougrirperfo'r^ionl^^^he cclls, or in a Cell Specialized in 

 Tell! ^floTcZrL^^^L^l form and structure, the spore case. 

 jL^^^'^h^olti^gitretTo? The entire contents of the spore 

 Kemer"*'^'""'*'™'"''*"" case may form a single zoospore, 

 or it may divide into several or many. The zoospores are 



