Ix THE BEGINNINGS OF LIFE. 



the branching of the thread is not sufficient, or the mode 

 of branching. Cladophora glomerata assumes a multitude of 

 forms which it would "be rash in the extreme to separate, 

 and it may be safely affirmed that of published species of 

 Cladophora and Conferva, at least one-half will ultimately 

 be reduced. Where Conferva are exposed to drought, they 

 sometimes throw down roots from their joints in search of 

 moisture, a circumstance which must be taken into account 

 in the estimation of species. In Lyngbya muralis the threads 

 often anastomose, producing a very curious and puzzling 

 appearance. ... In Anabaina and allied genera, the number 

 and disposition of the fertile cells will not afford safe cha- 

 racters ; nor will mere microscopic measurement, which is 

 often deceptive, and should be always taken with consider- 

 able latitude amongst Oscillatorice. The zoospores even of 

 the articulated Algae are not absolutely constant. Monstrous 

 forms occur in the small zoospores of Cladophora, and the 

 large ones of JEdogonium. Characters like those in Hassal's 

 Fresh Water Algae, dependent simply on comparative size, 

 are altogether inadmissible, as specific distinctions.' 



From a study of some of the Oscillatorice, and more 

 especially of Lyngbya muralis, Dr. Hicks 1 has not only 

 ascertained that these plants take on many distinctly differ- 

 ent modes of growth from time to time, but that they also 

 frequently throw off some of their terminal cells in the form 

 of gonidia, which straightway proceed to undergo a process 

 of segmentation after the fashion of the gonidia of Lichens, 

 so as to produce a palmelloid growth, which frequently 

 assumes the form of Protococcus viridis. Some of the cells 

 of these, after a time, may again take on the linear mode 

 of growth, and so revert to the original Lyngbya type. At 

 other times, by the occurrence of a lateral mode of segmen- 



1 'Journ. of Microse. Science,' 1861, p. 157. 



