568 DR. J. B. HICKS ON THE GONIDIA AND 



masses of green cells are produced having all tlie characters of the Palmellacese ( Chlo- 

 rococcns, Scematococcus, Goelocapsa, Sorospora, Falmoglcea, &c.), and [in the case of 

 Collemci] of Nostoc, and prohably the Nostochacea?, perfectly undistinguishable from the 

 so-called true forms ; and therefore it would be impossible to assert that any given mass 

 of these growths was not the segmenting gonidia of these Thallophytes. 



Hence, in the papers just mentioned, I have dwelt strongly upon the uncertainty 

 attending the ranking of these as independent organisms, and the great necessity there 

 is for re-examining carefully the entire subject afresh and witli the advantage of the 

 clue furnished by the observations above alluded to. 



It is with the view of assisting in the solution of this difficult inquiry that I have 

 brought forward the following observations — not with the presumption of being able by 

 them to clear up the question finally, but to add information to that already acquired, 

 upon which to make inferences regarding the separate entity of these forms — and also 

 of introducing some other facts interesting to the vegetable physiologist. 



The term gonidium has been applied to the single cell thrown off by the thallus- 

 producing plants, and is probably the simplest homologue of the gemma of the higher 

 Cryptogamia. The gemmae of the higher kinds, consisting of several cells, are capable 

 of growing out at once into the peculiar species from which they spring, by a process 

 purely vegetative and agamic *. The gonidia of the Thallophytes have also the same 

 power under certain circumstances {e. g. the sori of Lichens) ; and, besides this, they 

 have been known to have the power of simple subdivision prior to their forming the 

 perfect plant. That they have a far more varied and extensive proj)erty of multipli- 

 cation than was originally supposed, I have shown in tlie papers quoted. That the pro- 

 duction of gonidia is not confined to the Thallophytes, but may be abundantly traced in 

 the Mosses, will be one of the endeavours of this communication to point out. 



But, whereas in the Thallophytes they can be produced upon almost any part of the 

 plant, except upon that especially set apart for gamic reproduction (if such be the true 

 nature of the apothecia and spermogones of Lichens, or of the receptacle of the 

 Hymenomycetes, &c.), we shall find, on the other hand, that in Mosses a particular 

 portion is set apart for their production, — though it must not be understood that the 

 other portions of the plant cannot produce them ; for, as I shall be able to point out 

 hereafter, under peculiar circumstances almost every part is so capable. 



These observations were made upon a variety of our own common native Mosses, 

 Bryum, Neckera, Polytrichiwn, Sypmim, Tortula, &c. They aU. showed, equally well, under 

 the same circumstances, the phenomena to be mentioned, as far as I was able to judge. 



If we examine any Moss, more particularly in the early spring, about its base, just at 

 the junction of the true roots with the ascending axis, we shall almost invariably find, 

 where the axes of different plants do not grow together too closely, green filaments, of 

 indefinite length, springing out and liranching, the branches frequently interlacing 



* The exact value of the distinction between the simple gonidium, tubercle, gemmule, propagule, does not appear 

 clearly marked : transitions continually occur between each and all of them. The first certainly tends more parti- 

 cularly to multiplication by the production of separate cells ; the latter kinds to the extension of filaments leading 

 more directly to the formation of the leafy axis. 



