CHAPTER XXV 

 STUDIES IN CRYPTOGAMS 



The special advanced pupil who has acquired skill in 

 the use of the compound microscope, may desire to make 

 more extended excursions into the cryptogamous orders. 

 The following plants, selected as examples in various 

 groups, will serve as a beginning. 



The alga9 comprise most of the green floating "scum" which 

 covers the surface of ponds and other quiet waters. The masses of 

 plants are often called "frog spittle." Others are attached to stones, 

 pieces of wood, and other objects submerged in streams and lakes, 

 and many are found on moist ground and on dripping 

 rocks. Aside from these, all the plants commonly known 

 as seaweeds belong to this category. They are inhab- 

 itants of salt water. 



The simplest forms of algae consist of a single 

 spherical cell, which multiplies by repeated division or 

 fission. Most of the forms found in fresh water are fila- 

 mentous, i. e., the plant-body consists of long threads, 

 either simple or branched. Such a plant-body is termed 

 a thallus. This term applies to the vegetative body of 

 all plants which are not differentiated into stem and 

 leaves. Such plants are known as tliallophytes (325). All 

 algsB contain chlorophyll, and are able to assimilate car- 

 bon dioxid from the air. This distinguishes them from 

 313. Strand of the fungi. 



s^fo'wTn*' Spirogyra. One of the most common forms of the 



the chloro- green algae is spirogyra (Fig. 313). This plant usually 

 There & S a forms the greater part of the floating green mass on 

 nucleus at a. pon d s . The filamentous character of the thallus can be 

 seen with the naked eye or with a hand-lens, but to study it care- 

 fully a microscope magnifying two hundred diameters or more should 



(178) 



