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CHAPTER VII. 



CELLS OCCURRING AMONGST THE LOWER PLANTS. 



Having now examined some of the most important elements 

 going to build up the tissues of Higher Plants, it becomes 

 necessary for the student to inquire into the structural details of 

 cells as they occur amongst the Lower Plants; and in this 

 respect it will be convenient to start by examining briefly the 

 chief form of cell met with in the Fungi, and then to take a few 

 well-marked types occurring amongst the Algae, and examine 

 these in detail. Many of the Algse are Unicellular organisms, 

 and, as such, are easy to study ; they are, moreover, very 

 interesting, since in them vital processes occur which are often 

 diflBcult to demonstrate in the cells of higher plants, but which, 

 in these types of lower organism, escape the confusion often 

 consequent on the examination of complex tissues. 



A. Cells occurring amongst the Fungi. 



In the more highly differentiated members of the Fungi, 

 although certain variations occur, the tissues are composed of 

 cells* which conform to a simple type — viz., a tubular or 

 parenchymatous thin-walled element. The cells are joined 

 together to form long filaments, which are known as hyphae, and 

 sections of fungal tissues generally show a dense interwoven 

 mass of these hyphse, cut across in many directions. In a few 

 members — viz., the Lichens — algal cells are found living 

 together with hyphse, forming what is known as a symbiotic 

 commTinity; and these plants are often propagated by small 

 masses known as soredia, composed of a certain number of hyphse, 

 amongst which are embedded a few algoid cells. 



* Each of these ao-oalled cells is in reality a "ooenooyte" — viz., it 

 possesses many small nuclei — and is thus composed of many potential 

 protoplasts. 



