86 FLOWERLESS PLANTS 



weather, where they form a greenish stain. 

 Individually, these plants are very minute, and 

 when in a dr^' condition they frequently float 

 about in the atmosphere, tiny specks of hfe 

 waiting for an opportunity to start life afresh 

 in some damp corner. Certain of these small 

 algae have entered into the strange alliance with 

 the lichen-making fungus, a matter which is 

 fuUy discussed in another chapter. The mys- 

 terious Nostoc, which often appears after rain 

 on paths in gelatinous masses, is due to the 

 formation of colonies of certain algae, which, 

 prior to the coming of the moisture, have been 

 in a drj' resting state. In this condition they 

 are quite invisible, and the almost magical 

 manner in which the Nostoc appears after rain 

 was very mystifying to the early observers. 



Many of the microscopic algas to be found in 

 water are exceedingly beautiful objects. The 

 Desmids and Diatoms have for long been the 

 admiration of those who have taken the pains 

 to study them with the aid of a microscope. A 

 few drops of pond water will often show a vast 

 variety of forms, many of which are most pleas- 

 ing in design. Not a few of these strange little 

 plants are free swimming, and move about in the 



