86 THE HISTORY OF CREATION. 



and which possessed the form of a single plastid. At 

 first the entire body of one of these small primary plants 

 consisted only of a most simple cytod (a plastid without 

 kernel), and afterwards attained the higher fonn of a 

 simple cell, by the separation of a kernel in the plasma. 

 (Compare above, vol. i. p. 345.) Even at the present day there 

 exist various most simple forms of Algae which have devi- 

 ated but little from the original primary plants. Among 

 them are the Algse of the families Codiolacese, Protococ- 

 cacete, Desmidiacepe, Palmellacese, Hydrodictyese, and 

 several others. The remarkable group of Phycochromacefe 

 (Chroococcacese and Oscillarinefe) might also be comprised 

 among them, unless we prefer to consider them as an in- 

 dependent tribe of the kingdom Protista. 



The monoplastic Protophyta — that is, those primary Algas 

 formed by a single plastid — are of the greatest interest, 

 Tiecause the vegetable organism in this case completes its 

 whole course of life as a perfectly simple " individual of the 

 first order," either as a cytod without kernel, or as a cell 

 containing a kernel. 



Among the primary plants consisting of a single cytod are 

 the exceedingly remarkable Siphonese, which are of con- 

 siderable size, and strangely " mimic" the forms of higher 

 plants. Many of the Siphonese attain a size of several 

 feet, and resemble an elegant moss (Bryopsis), or in 

 some cases a perfect flowering plant with stalks, roots, 

 and leaves (Caulerpa) (Fig. 17). Yet the whole of this 

 large body, externally so variously differentiated, consists 

 internally of an entirely simple sack, possessing the negative 

 characters of a simple cytod. 



These curious Siphon epe, Vaucherise, and Caulerpje show 



