246 APPLIED BIOLOGY 



are so simple that there is no differentiation of the plant- 

 body into roots, stem, and leaves. Some of these lower plants 

 have chlorophyll and are called Algae ; and some (the Fungi) 

 have no chlorophyll. All these simple plants belong to the 

 lowest division of the Thallophytes. See table of plant 

 classification in 133. 



1. LOWER SPORE-PLANTS WITH CHLOROPHYLL : ALG^J 



236. The lowest spore-plants without root, stem, and 

 leaves and with chlorophyll are often grouped together 

 under the name Algae.* These are numerous forms, rang- 

 ing from microscopic plants to the large sea-weeds. Most 

 of the algae live in fresh or salt water, but a few can live in 

 moist places on soil and surfaces of larger plants, and even 

 occasionally undergo drying. 



In this course we cannot take time for more than a brief 

 study of a few common types whose life-activities help us 

 to a better understanding of some of the general principles 

 of biology. But the reader should understand that such 

 a condensed account as that which follows cannot be more 

 than a beginning study of a few examples in a great group 

 of low plants upon which much emphasis is laid in advanced 

 courses of botany in colleges. In the present study we can 

 do little more than direct attention to the ways in which 

 these simple plants solve the problems of the fundamental 

 life-activities of feeding, moving, breathing, excreting, and 

 reproducing processes which we have now traced through 

 a series of plants, beginning with the highest or seed-plants. 



The following descriptions of common types of algae should 

 be accompanied as far as possible by demonstrations and 

 laboratory study. 



* A few of the highest algae (e.g., the freshwater Chara and Nitella) have 

 structures serving as roots, stems, and leaves very much as might a moss 

 plant entirely submerged in water. 



