Phaeophyceae 



185 



of the Phaeophyceae. These three should be Ectocarpus (or 

 Pylaiella), Cutleria, and Fucus. Cutleria is not found on the Ameri- 

 can coasts, but is abundant at Naples. The habits of gametophyte 

 (known as Cutleria) and the sporophyte (known as Aglaozonia) are 

 so different that they furnish a good illustration of alternation of 

 generations. Beginners understand such an illustration more readily 

 than they do an illustration like Dictyota, with its two generations 

 looking so nearly alike. Cutleria also furnishes a good stage in the 

 evolution of sex, about midway between isogamy and the extreme 

 hetrogamy of Fucus. 



For habit study, both generations should be mounted upon paper. 

 The gametophyte (Cutleria) 

 sticks well, but the sporo- 

 phyte (Aglaozonia) will 

 need some glue or gummed 

 paper. 



For paraffin sections, fix 

 in chromo-acetic acid. Cut 

 10 ju thick. For mitotic 

 figures, some osmic acid 

 should be added to the 

 chromo-acetic acid and the 

 sections should be much 

 thinner, about 3 to 5 ju. 

 Use iron-haematoxylin and 

 then stain for 3 to 5 minutes in alcoholic safranin (Figs. 43, 44). 



Fucus. Material for habit study may be dried, or preserved in 

 formalin, or mounted on paper. In the latter case, glue or gummed 

 paper will be necessary. Most satisfactory of all is to send to Woods 

 Hole, Massachusetts (George M. Gray), for living material. Fertili- 

 zation occurs at all seasons, but autumn is the most favorable. In 

 summer the material dies before it reaches Chicago, but during the 

 rest of the year a pailful will reach Chicago, and even as far west as 

 the Mississippi River, in good condition for showing the rotation of 

 the egg by the sperms. The eggs and sperms form slimy masses, 

 the antheridia being orange red, and that containing the eggs a dirty 



FIG. 44. Cutleria multifida: photomicrograph 

 from a preparation by Dr. S. Yamanouchi, show- 

 ing a sorus of antheridia; thickness, SM; stain, 

 iron-alum haematoxylin. XI 70. 



