^ 



l:p^^ 



le 



proceed , 

 4 ^^^s tell. 



APPENDIX D. 



Ivii 



ance of J7^ 



X 





Coccochkrh, Hassalj 

 disappears, and 

 nd form an indefinit 



, Hicks believes 



; form of the ori^^ii 



no means all that », 

 of the gonidial law 



.d into a Pd^4' 

 .uishable froiB o'J| 



ationsofaso^^'^'^ 



f had a so ^^'' 



extent, haa 





i855 



every form of Hemaiococcus {Gleocapsa, Kiitzing), and also 

 almost every form of Coccochlorh {Palmoglcee, Kiitzing) as 

 well as that of Sorospora virescens — that is to say, from the 

 gonidia of a single Lichen there may be produced, by slight 

 variation of the ' conditions ' under which they grow, no less 

 than twenty-three forms, which have been hitherto regarded 

 as distinct species of fresh- water Algse. 



But even this is not all ; such algoid forms may have other 

 totally different modes of origin, to some of which we shall 

 afterwards allude (see pp. Ixiii-lxviii, Ixxiii, Ixxv, and Ixxxviii). 



^^^^ is exceediajlj ] Itzigsohn ^ and J 



^^ge oval cells is ^ 



mucous layer, preciseH nates from a Lichen called Collema; and their observations 



had both insisted upon the fact 



Nosioc 



have since been confirmed and extended by Dr. Braxton Hicks. 

 They had observed the development of Nosioc from changes 

 taking place in a small ball of jelly-like mucus enclosing 

 two or three beaded cells, which becomes extended from 



)y the condensatioiiOf| the Cf?//ma-thallus. Such a jelly-ball may undergo one or 



by the enlargement 



* 1 



other of two developmental phases : first, it may produce 

 continuous colourless threads, and may thus again pass into 

 is disposed to befacf Collema; or, secondly, it may develop no colourless fibres,. 



but the ball may grow in size and transparency, whilst the 



green-beaded filaments within increase by subdivision, and 



the heterocysts, common to the NostochacecBa 



intervals. This second mode of development, according to 



Itzigsohn and Sachs, may continue for an indefinite period. , 



Dr. Hicks describes still another mode by which Nostoc 



^'"'^"' n.Wt ^^^ originate from Collema. Within the thallus of this 



h, hovre^ '^^^^^p^ Lichen certain gonidia appear, which are larger and of a 



lighter green than the others. These, when liberated, undergo 

 segmentation for a time, so as to produce a small Chloro- 



(^(^^^^^-mass. Soon, however, the products begin to take 



1 ( 



Botan. Zeitung/ 1854, p. 521. 



^ Loc. cit. 



