HOW TO KNOW THE SEAWEEDS 



white card under a dissecting microscope of 6 to 10 power and sliced 

 with the blade against a finger nail for support and guide. 



Calcareous algae present special difficulties in sectioning and must 

 be decalcified and dehydrated with alcohol, embedded in paraffin 

 and sectioned on a rotary microtome. Sectioning and staining proce- 

 dures may be found in accounts of botanical microtechnigue, such 

 as Johonsen's Plant Microtechnique, McGraw Hill & Co., 1940. 



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