66 



BOTANY. 



cell-families ; in both cases separate motile cells (zoospores) in a mother- 

 cell arrange themselves in a definite manner, and gradually unite into 

 a family resembling the parent plant (Fig. 49). By the breaking up of 

 the wall of the mother-cell the new family is set free. 



(6) In some fungi the cells composing the vegetative threads (hy- 

 phae) unite loosely with one another into a mass. In some cases the 

 union is so slight that the hyphae may be separated with the greatest 

 ease, while in others it approaches the density and firmness of true 

 tissues (Fig. 50). While the term Cell-Family may be applied to such 

 aggregations of cells, the common one of Spurious Tissue is to be pre- 

 ferred.* 



(c) In the embryo sac of Phanerogams the cells are at first sepal ate; 



Fig. 50. Rkizomorpha subcorticalis (the compact mycelium of a fungus). The 

 left hand figure shows a longitudinal section of the growing end of a young shoot. 

 The right hand figure shows a cross-section of the came ; a, the central pith-like por- 

 tion ; 6, the cortical portion of smaller cells ; A, the hairy coat, which is often 

 wanting. X 100. After De Bary. 



these afterward unite into a mass which cannot be distinguished by 

 any structural character from a true tissue. (See Fig. 33, p. 43.) As, 

 however, the component cells were originally separate, the resulting 

 mass must be classed with the spurious tissues. 



94 (3.) Fusions. It frequently happens that the separat- 

 ing walls of contiguous cells are absorbed and their cell- 

 cavities merged into one. In this way long tubes (vessels) 



* This is the " Tela contexta ' ' of some authors. 



