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XXXIII. Observations on the Gonidia and Confervoid Filaments of Mosses, and on the 

 relation of their Gonidia to those of Lichens and of certain freshwater Algce. By 

 J. Bkaxton Hicks, M.D. Lond., F.B.S. and L.S. 



Read June Sth, 1862. 



-T OR a considerable time it has been known that tbe Thallopbytes throw off certain 

 single cells, called gonidia, which are capable of reproducing the species from which 

 they spring. It has also been known that, to a limited extent, they possess the power 

 of segmenting before they produce a new thallus. The observations of a few Con- 

 tinental natiiralists * pointed out that they could not be distinguished optically from 

 the then-called Protococcus-iovvas {Chlorococciis). 



These observations, however, had attracted but little general attention to the matter. In- 

 deed their tendency was such that, fully carried out, they necessitated a reconsideration of 

 all the PaLmellaceee or pseudo-uniceUular Algae (Braun) and of the true unicellular Algse 

 (Braun) . The contemplation of such a revision might well be considered sufficient to alarm 

 even the most persevering systematist ; for it involves the very arduous task of watching 

 the growths classed under these heads throughout a long period, and under every possible 

 change of external conditions, with this additional difficulty, that, in case the observations 

 produced no decisive result, they could not be admitted as absolute evidence that these 

 forms were really unalterable, because the conditions to which they were thus exposed, 

 perhaps, might not include all the combinations of influences to which they were liable 

 in their natural state. Besides this, there is the fact already pointed out in the course 

 of my observations on the gonidia of Lichens t» which increases the difficulty of 

 proving the separate existence of these and allied growths, namely, their continuing in 

 the same form of existence for an indefinite period, segmenting continually, till ex- 

 ternal conditions are favourable for inducing a change in the mode of growth, in which, 

 again, they may continue for an equally indefinite period, and so on in every phase 

 through which they are capable of passing. I believe the task just indicated has not yet 

 been continuously undertaken ; and at present any attempt at fixing the true position 

 of these organisms would be completely vain and disappointing till more extensive re- 

 searches in all directions shall furnish sufficient materials on which to argue. 



The observations on the development of the gonidia of the Lichens, which I have 

 brought forward in the ' Journal of Microscopical Science,' 1860 (July and October) 

 and 1861 (January), also on the growth and diamorphosis of Lynghya muralis, and 

 on the statospores % of Volvox in 1861, show that from these plants large quantities and 



* E.g. Meyen, Itzigsohn, Kiitzing. t Quart. Journ. Mic. Sc. 1860-61. 



X See the remarks ou this point by Pringsheim, in relation to this subject, on the " chronispores " of Hydro- 

 dictyon. Translated in Quart. Journ. Mic. Sc. April 1862. 



VOL. XXIII. 4 G 



