1^. Thallophyta and Bryophyta 



This chapter brings together plants and plant organs that require 

 essentially similar treatment. For instance, a segment o£ mushroom 

 cap, a liverwort thallus and a moss gametophyte may well be prepared 

 for sectioning by identical methods. Filamentous algae, free-floating 

 filamentous fungi and moss prothalli also present similar problems. 

 Fungi that live within tissues of higher plants will be discussed in terms 

 of the responses of the fungus and the host to processing. 



Algae 



The most satisfactory method of studying algae is by the use of 

 fresh living material in conjunction with well-preserved bulk mate- 

 rial. Except for some critical cytological features, most of the life 

 history can be worked out without stained preparations. Stages that 

 have short duration must be preserved when available and subse- 

 cjuently studied from temporary mounts. However, permanent stained 

 slides are indispensable for research and have a legitimate place in 

 teaching to supplement bulk material. The methods of processing 

 the most commonly used algae are outlined briefly in this chapter, 

 with frequent references to the whole-mount methods in Chap. 10. 



GREEN ALGAE 



These plants exhibit a wide range of size, complexity of organiza- 

 tion, and habitat. The following simple precautions should be ob- 

 served in collecting, transporting, and storing plants: 



1. Keep the plants in their natural substratum (water, soil, bark 

 of tree) until the moment of killing. 



2. Avoid subjecting the plants to excessive heat or to desiccation 

 during storage or transportation. 



3. Unless culture methods have been carefully worked out, kill 

 the plants as soon as possible after collecting. 



4. Subdivide or spread out large masses of material to promote 

 rapid killing and hardening (fixing) . 



5. Keep intact the organization of the filament, or other type of 

 colony. 



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