FUCUS SERRATUS 209 



their broader, free end crowned by a tuft of hairs : these are 

 young plants of Fucus, or of one of the allied genera. 



Having collected such material, and treated it as above directed, 

 tease it out with needles, in glycerine, and examine the plants 

 thus separated under a low power : the following points are the 

 most worthy of note 



1. The nearly spherical form of the very young plants, which 

 consist of but one, or of relatively few cells, and are limited 

 externally by a definite cell-wall, the formation of this wall is the 

 first obvious change after fertilization. 



2. The elongated club-shape of the older plants. 



3. Their terminal depression, from which numerous hairs 

 protrude. 



4. The mode of attachment by means of hypha-like threads 

 of independent growth, similar to those seen in the older plants : 

 some of these threads may be seen quite young, and not yet 

 attached to the substratum. 



From such plants as a starting-point, intermediate forms will 

 lead on to the mature Fucus plant. 



