286 THE BIOLOGY OF THE PLANT 



Method of Examination. — ^Laboratory specimens, if 

 living, should be studied in sea water; if alcoholic, in 

 fifty per cent, alcohol. Sections are most easily cut from 

 the preserved specimens and must be examined in a mixt- 

 ure of glycerine and fifty per cent, alcohol. ' Sections 

 of fresh material should be studied in sea water or in 

 a mixture of three parts of salt to one hundred parts of 

 fresh water. Inland students may sometimes be fortu- 

 nate enough to see the extrusion of the sexual cells, if 

 plants gathered at high tide be sent them, accompanied 

 by a supply of sea water. On receipt of the plants 

 they should be divided into two sets. Place the first set 

 in the sea water. Hang the second set in a cool place. 

 Leave both sets for about six hours. During that time 

 some of the hanging plants will probably have extruded 

 their sexual cells, the male cells or antheridia being 

 orange-yellow, the female cells or oogonia olive. Then 

 hang up the plants which have been in water, and place 

 the hanging plants in the water for about six hours. 

 This may be repeated a great many times. 



MOKPHOLOGT 



NaTied^eye Characters. 



a. General appearance. — If possible study the plant 

 as it grows, attached to the face of a rock or to 

 the surface of a timber. E"ote its relation to the 

 tide marks, its rise and fall with the tide, etc. 

 Dig dqwn into a mass of the plants left exposed 

 by the faU of the tide, and note the differences 

 between those plants which are on the surface 

 and those deep down in the mass. Then examine 

 an entire fresh or preserved specimen. "What is 

 the general shape of the plant-body, or, as it is 



