CONPERVOIDE^. 



407 



tion into distinct fragments, which have a common origin, but an indi- 

 vidual life. They multiply by spontaneous division, as represented 

 in fig. 194, Nos. 6 and 7 ; and are generally found attached to the stems 

 of other plants immersed in water, or floating in pools or ditches. 



In the algae, the seeds are imbedded either in the frond itself or 

 in some especial recep- 

 tacle ; the fronds develop 

 cellules, in which the re- 

 productive nucleolus is 

 enclosed ; and acquiring 

 a deeper colour with age, 

 becomes finally a sepa- 

 rate plaat. The higher 

 kinds of algae inhabit 

 sea-water only ; they 

 then assume the forms 

 of more perfect plants, 

 forming vast submarine 

 forests of the most lux- 

 uriant vegetation. A 

 few species are repre- 

 sented in our frontis- 

 piece. Many kinds fur- 

 nish to man a whole- 

 some and palatable food : 

 the Laver of our sea- 

 shores, the Carrageen, 

 or Irish Moss, with 

 others, belonging to this 

 group ; and from them 

 are formed the edible birds'-nests, which are considered so great a 

 delicacy by the Chinese. That valuable medicinal substance. Iodine, is 

 also procured from certain algse.* 



We now arrive at a more complex form of cell, one that has at- 

 tracted the attention of all microscopists from its earliest discovery to 

 the present day. It was for a very long time classed with the lower 

 forms of animal life; and there it remained, for the micro-chemical in- 

 vestigators of the present time to settle the perplexing question, and 

 by truly assigning to it a place amongst vegetables. The cell referred 

 to is recognised as the Volvox globator, or revolving-cell, represented 

 • For further information see Dr. HasBallon the Fresh- Water Algce. 



fig. 194. 

 Volvox globator. 2. A section of volvox, showing the 

 ciliated margin of the cell. 3. A portion more highly 

 magnified, to show the young Volvioinse, with their 

 nuclei and filamentary attachments. 4, 5, 6, and 7. 

 ConfervoidesB, showing their modes of growth. 



