CHAPTER XXIII. 



Some Types of Plowerless Plants.^ 



265. Numerous Classes of Gryptogamous Plants. — While 

 there are only two classes of flowering plants (§ 256), and only 

 the latter of these need occupy much of the attention of a 

 beginner in botany, there are some fifteen classes of flower- 

 less plants, so that an elementary book on botany can only 

 make the student acquainted with a few specimen groups 

 chosen from among these. 



THE STUDY OF PROTOCOCCUS.* 



266. Occurrence. — Protococcus may be found in the water of 

 stagnant pools, particularly of those which contain the drainage of 

 barn-yards or of manure-heaps. It occurs also in the mud at the bottom 

 of eaves-troughs, in barrels containing rain-water, or in water standing in 

 cavities in logs or the stumps of trees. Water containing Protococcus in 

 abundance is greenish (or sometimes reddish) throughout, while examina- 

 tion with the naked eye hardly shows the separate particles to which the 

 color is due. Portions of the mud on which the plant occurs should be 

 carefully scraped ofl and kept damp for examination, or the water in 



1 The author has introduced the study of a few cryptogamous forms thus late in 

 the present book more out of deference to general usage than because he thinks it to 

 he the best possible order of treatment. He has found it desirable to exhibit (under 

 the microscope) and discuss slides of Protococcus. Pleurococcus, Palmella, and so on, 

 as soon as the pupil is shown the cellular structure of seeds. This emphasizes and 

 makes clear at the outset something of the nature of the vegetable cell. Protococcus 

 and Spvrogyra may he examined for chlorophyll, and their liberation of oxygen in 

 sunlight noted whUe the work of the leaf is under consideration. Finally the 

 structure and the reproduction of all the cryptogamous forms which are to be 

 considered at all, may be investigated and discussed just before the study of the 

 flower is begun. 



2 See Huxley and Martin's BMogy (extended by Howes and Scott) under 

 Protococcus. 



