164 HICKS, ON THE DIAMORPHOSIS OF LYNGBYA, ETC. 



I have not been able yet to observe tlie formation of 

 zoospores in the Prasiola derived from Lyngbya muralis: still 

 future research may be more successful. It might be a 

 question, upon which it would be out of place to enter here, 

 whether the formation of zoospores be a sufficient generic 

 sign, or rather, if it should not be considered a non-essential 

 variety of vegetative growth. 



The relation of Lyngbya and Prasiola to the Palmellacese, 

 by means of the gonidia and their changes, I have already 

 pointed out ; and I shall only mention that Meyen's paper * 

 seems to have had no effect in leading to the study of the 

 history of these simple organisms. Jessen even remarks, 

 that if Prasiola produces Protococcus viridus, " Protococcus 

 viridusm. Prasiolam certe transit." The remarks of Itzigsohn 

 upon some forms of these simple cells, and their relations 

 to the lichens, have produced no effect in this country, but I 

 hope these remarks, with those I have already brought 

 forward in this Journal, and others I have yet to bring forward, 

 will lead to their further study. 



Thus it seems that we cannot but conclude that Lyngbya 

 muralis, Schizogonium, and Prasiola, are but difl'erent stages 

 of the same organism, which, with the segmentation of their 

 gonidia into the Palmelloid cells, form a cycle of phases, each 

 of which has a powerful tendency to recur in shorter cycles 

 to the form which pi'eceded it. 



This leads one to the interesting question, which is the most 

 perfect condition in the chain ? 



This can scarcely be answered till we know in what relation it 

 stands to other plants. Is it an independent growth, or has it 

 another origin yet unsuspected ? And if we decide in favour 

 of the former we may, I think, very reasonably ask — are there 

 any other links to the chain ? For as yet we have no sexual 

 stage. If we consider carefully the mode of growth we shall 

 see there is really very little difference between any of them ; 

 the essence of all being the segmentation of the cells, linearly 

 in Lyngbya; collaterally, and held together by cellulose 

 in Schizogonium and Prasiola ; while it is free in the gonidia. 

 If the same processes be compared with that of the gonidia of 

 the Lichens, shown in this Journal,"^ there is nothing in them 

 that may not be included within the varieties of gonidial seg- 

 mentation. Not that by these remarks I am asserting it is 

 not a separate existence, but there seems to me to be an 

 equal probability of its being a gonidial stage or stages. At 



* 'Die IMetamorpliose des Protococcus viridis in Priestleya votrjoides und 

 Ulva terrestris.' 'Limisea,' 1827. 

 f 'Microscopical Journal,' Nov., 1860 ; January and April, 1861. 



