108 PRINGSHEIMj ON THE 



zoospores iuto motionless cells ; beyond this, their nature as 

 to their sexual value, is still uncertain. 



This is, perhaps, the best place to introduce an observation 

 made by ]M. Braun, relative to a new genus Codioliim, 

 Avhich that able phycologist has discovered in Heligoland. 



M. Braun tells us, that he has seen in the little tufts 

 formed by the plantules of Codiolum some rounded scattered 

 cells, the external appearance of -which and their chemical na- 

 ture treated by ordinar}^ agents, led him to suppose that they 

 belonged to Codiolum ; and he presumes that they probably 

 originated in a particular development of the zoospores. 



If these cells do, indeed, belong to Codiolum, of whicli we 

 can only be assured by observing their development from 

 the earliest beginnings, and further growth, it is probable 

 that they should be regarded as have been the chronizoo- 

 spores of the algte in question. 



Among the species of Cutleria again, the second sort of 

 zoospores which do not germinate immediately, and have, 

 for this reason, been ranked as true spores by M. Thuret, 

 may, very probably, after all, belong to this class of bodies 

 instead. In which case, Cutleria would not be so far re- 

 moved as it appears to be from its nearest allies, that is to | 

 say, all the other Fucoidcce ; and the opinion held by M. i 

 Thuret, on the nature and presence of the zoospores in ques- 

 tion, would agree better with the idea of their being the 

 chronizoospores of tlie Cutleriea, than with their being the 

 true spores of these algse. 



Since the knowledge I have acquired of the chronizoopores 

 of Hydrodictyon has given me a difinite aim to my researches, 

 I have never, with all my efforts, been able to meet with 

 more than one other example, and that in a very different 

 family of the transformation of zoospores into chroni- 

 spores. 



The genera UlotJirix, ^tiycodonunn, CtKetopJiora, and Dra- 

 panialdia, which all belong to the small and badly defined 

 family of the Draparnaldiece possess, independently of their 

 well known spores, hypuospores, or motionless spores (Rube- 

 sporm), whose development presents, according to the genera 

 or species examined, differences only of very secondary im- 

 portance. 



In the genus Ulothrix, nearly all the cells of the plants 

 produce hypuospores. In each of the cells a single large i 



hypnospore is formed, which soon fills the whole cavity, and \ 



afterwards distends it by its growth. During this genera- 

 tion the contents of the cells and their membranes undergo 

 modifications which betoken an approaching suspension of 



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