74 ZYGOPHYCE^E. 



ORDER II. ZYGOPHYCE^. 



Either unicellular or multicellular Algas, with terminal vege- 

 tation, and destitute of true ramification. Cells single, or 

 segregate, or geminate, or united in a series. Chlorophyll-mass 

 for the most part distributed in plates, or bands, including one 

 or more amylaceous granules. 



Multiplication by division of the cells in one direction. 



Propagation by zygospores resulting from the conjugation of 

 two cells. 



Consult here Dr. A. De Bary's " Untersuchungen uber die Familie 

 der Conjugaten." Leipzig, 1858. 



FAMILY I. DESMEDIE^S. 



Unicellular Algas. Cells for the most part compressed, 

 single, or segregate, or geminate, or a larger number united in 

 a band, or filament ; variable in form, usually constricted in the 

 middle, so as to constitute two symmetrical semi-cells. 



This large and interesting family is designedly excluded from the 

 present work, as it is proposed to treat them separately. As so many 

 students confine themselves exclusively to this family, this proposal 

 will doubtless commend itself. The excellent text book by J. Ealfs has 

 long been the standard for English students, and would be so still but 

 for its scarcity, and the large number of additions in. the interval since 

 its publication. 



FAMILY II. ZYGNEMACEJB. 



Multicellular Algas. Cells cylindrical, equal at both ends ; 

 fructiferous cells more or less tumid, or inflated, all closely 

 conjoined in filamentous families, forming an articulated simple 

 thread, with a centr;.! cytioblast involved in radiating proto- 

 plasm. Cell walls lamellose. 



Chlorophyll-mass effused, or of a definite form, often forming 

 a spiral band. 



Vegetation by repeated transverse division. 



Propagation by zygospores, resulting from the conjugation of 

 two cells. Conjugation taking place in three ways, lateral, 

 scalariform, and genuflexuous. 



This family is sub-divided into three sub-families, according to the 

 character of the reproductive process : 



I. ZYGNEME.E. 



II. MKSOCARPE.E. 



III. GONATONEME.E. 



