32 



LECTURE III. 



the second main function of roots, to be organs of attachment, asserts itself promi- 

 nently. 



We may first consider the genera 

 Fucus and Laininaria, including 

 large plants which are also highly 

 organised anatomically; here we 

 find the base of the whole plant an- 

 chored fast to stones, rocks, &c., by 

 means of a much-branched root. 

 The attempt to penetrate into a nu- 

 tritive substratum is hardly made, 

 since it is superfluous, as has been 

 said ; it suffices here that the roots 

 cling as organs of attachment to 

 any solid body, since the whole 

 surface of the plant takes up food, 

 but is also exposed to the brunt 

 of the waves. If the student has 

 made himself sufficiently acquaint- 

 ed with the peculiarities of the typi- 

 cal roots described, there cannot 

 be the slightest doubt that these 

 organs of attachment of the large 

 sea-wracks are roots, in which the 

 function of nutrition is a second- 

 ary matter. Their anatomical and 

 cellular structure corresponds with 

 the whole character of the plant ; 

 these roots consist of masses of 

 tissue as do those of the vascular 

 plants, and they are branched 

 dichotomously like those of the 

 LycopodiacecT. 



If we then proceed to Algae of 

 simpler structure, we meet among 

 others with the group Characeas, 

 the roots of which agree in most 

 essential peculiarities with those of 

 the Mosses — simple cell-filaments 

 with oblique cross-walls, which 

 penetrate into the substratum and 

 become branched there. Finally 

 are to be mentioned here the roots 

 of the non-cellular Algae, with 

 which we have become acquainted already in the genus Botrydmm (cf. p. 4). It is 

 obvious that in these essentially non- cellular plants, the much-branched roots are 



Fig. 22.— Entire plant of Laminaria CL 

 bb o'd leaf divided up; i'*' newly arising le; 

 from the growing point e ; y boundary betwi 

 At f. the new leaf is beginning to split ; at a- ; 

 (J nat. size). 



