SUMMARY OF ALGJE. 137 



endochrome, diffused through the protoplasm, without 

 distinct chlorophyll-grains, starch-grains, or nucleus — the 

 Chroococcaceae, the simplest form of the Phycochromacese, 

 or Cyanophyceae, which attain their highest development in 

 the Nostochineae, including the Oscillariacese, Rivulariaceee, 

 Scytonemaces, and Nostocaceffi. To them are probably 

 related the Diatomacese, which the author regards as a 

 simple form of life, probably not nearly connected with the 

 Conjugatse. 



The third series, or Chlorophyllophyces, is the only one 

 which has developed into the higher forms of vegetable 

 life. It is characterized from the outset by the cells pos- 

 sessing a nucleus, starch-grains, pure chlorophyll, and, in 

 certain states, a true cell-wall of cellulose. The lowest 

 family — the Protococcacese — exhibit further development in 

 two directions : the perfection and differentiation of the 

 individual cells, and the association of the cells into colonies, 

 or coenobes. The latter tendency leads to the Sorastre^e, 

 Pandorines, and finally to the Volvocineae. The further 

 differentiation of the individual cell has advanced one stage 

 in the Eremobiae or Characiaceae, from which are derived 

 the Multinucleatae, comprising the Siphonocladaceas and 

 Siphonese. The striving after a high development by the 

 elaboration of a single cell culminates in Vaucheria, or in 

 such forms as Acetabularia. 



Cell- division is already well displayed in the Confervoideae 

 isogamas, including the Chroolepideae, Ulotrichaceae, Con- 

 fervacese, and Pithophoraceas. From them evolution appears 

 to have taken place in three different lines : (i) the Con- 

 jugatae, including the Zygnemaceffi, Mesocarpeae, and Des- 

 mideas, which evidently came to an abrupt conclusion ; 

 (2) the Phaeosporeae, which led through the Cutleriacese and 



