xiv.] ALGAL. 209 



effects the ocean would be uninhabitable. No living 

 thing could exist within its bounds, and, instead of 

 being the highway of the world's commerce, it would 

 become unnavigable in fact, it would be one gigantic 

 cess-pool, the receptacle of the world's sewage. 

 Instead of the breezes from its bosom bringing the 

 health-giving iodine and ozone to mankind, it would 

 poison the whole atmosphere with its foetid emana- 

 tions ; and all along the coasts there would be deso- 

 lation and death for miles. Think, then, of the 

 importance of this tribe of plants, lowly as are their 

 position in the botanists' classification. Even the 

 minute confervas and diatoms of our ponds and 

 streams are of the utmost importance in purifying 

 the waters and sustaining the great numbers of 

 animals that subsist upon decaying substances. 

 Though the lowliest of all forms of life, they are, 

 nevertheless, indispensable to the higher forms; 

 and for this reason alone they merit some attention 

 from us who stand at the other end of the scale 

 of organisation. 



FIG. 156. Volvox globatot 



