FTTCTJS. 277 



in the flat upper region ; (6) the growing tips of the ordi- 

 nary sterile branches, showing a notch at the apex, or 

 two notches where forking has occurred; (7) the oblong 

 and thickened tips, or receptacles, of the fertile branches, 

 studded with (8) the projecting wart-like conceptacles 

 flask-like cavities, each opening by a pore (ostiole) 

 from which some hairs (paraphyses) may be seen pro- 

 jecting. 



If mature, it is easy to distinguish, on separate plants in 

 these two species of Fucus, the yellow or orange male 

 conceptacles containing the antheridia; and the dark- 

 green female conceptacles containing the oogouia. Also 

 note, scattered over the thin lateral wings in various parts 

 of the thallus, the small sterile conceptacles, which 

 contain only hairs. 



400. Material for Study. For part of the work on 

 Fucus it is essential to have fresh plants. Those residing 

 inland should get specimens sent to them from the coast ; 

 on arrival the specimens should be placed in sea-water, or 

 sea-salt solution. Fresh material may be kept alive in sea- 

 water, or in solution of Tidman's Sea Salt (5 oz. to a 

 gallon of tap-water). 



For study of the general habit of the plants, Fucus 

 material may be allowed to dry ; when required for use, 

 soak the dry specimens in water until they become soft and 

 flexible the same material can be used repeatedly in this 

 way. 



For microscopic work on the thallus structure use 

 material that has been hardened by being preserved in 

 either formalin or in 70 per cent, alcohol, or (better) 

 placed in 70 per cent, alcohol after being left for 24 hours 

 in fixing fluid consisting of 1 gram chromic acid and 

 0*4 c.c. glacial acetic acid to 400 c.c. of sea-water and then 

 rinsed well in sea-water. 



To make the brittle alcohol-preserved material easier to 

 cut, place the pieces in mixture of 1 part glycerine and 

 3 parts alcohol for 24 hours, or in glycerine for a shorter 

 time, or in equal parts alcohol and glycerine for a longer 

 time (2 or 3 days). 



