RECENT OBSERVATIONS ON THE GONIDIA QUESTION. 125 



whether we have to do witli a gonidium not yet coloured 

 green, or with a very young hypha-branch, because, as 

 has ah-eady been frequently mentioned by various writers, 

 even the very young green gonidia attached to the hyphaj are 

 not different in form from young hypha-brauches j how much 

 the more should this be the case with the younger still un- 

 coloured gonidia? 



After 1 had satisfied myself that this was the only direc- 

 tion in which the research must be carried out to furnish 

 wholly decisive results, I tried to gain my object by making 

 very thin sections from the lichen-thallus, which were then 

 treated with various reagents. I obtained the sections as 

 thin as possible by the method of Gibelli of embedding the 

 thallus in stearic acid. From the lump thus obtained, upon 

 cooling, a section is made as thin as possible ; afterwards the 

 thallus-sections were freed from the surrounding stearins 

 by means of a fine needle, or, better, by means of warm alcohol. 

 I never succeeded, however, in perceiving very young gonidia, 

 which were not yet coloured green, so that I did not thus 

 make any observation in the least supporting the origin of the 

 gonidia from the hyph(E. 



During the research it occasionally happened that I met 

 with detached gonidia with larger or small portions of hypha 

 attached, from which the contents were removed in conse- 

 quence of the treatment, and which had thus become com- 

 pletely hyaline, and seeming as if the hypha pressed some- 

 times a little into the gonidium. In order to satisfy myself of 

 the correctness of the observation, it was necessary to view 

 such a gonidium, by means of turning, from all sides. This, 

 indeed, was generally not possible, because the portions of 

 hypha attached to the gonidium were too long to admit of 

 rolling it over in all directions. That this is necessary in 

 order to arrive at any certainty as to the fact, follows from 

 the possibility of ocular deception, and from the fact that we 

 might have to do with a gonidium divided into two, between 

 whose secondary- cells the end of the stalk-cell had penetrated, 

 and we might only see the secondary cells superposed above 

 one another.^ Turning upon all sides showed me in very few 

 cases that hypha-ends had penetrated into a gonidium. In 

 uninjured gonidia — still with contents — I never saw it; 

 a priori, one might certainly say that in such a case the 

 observation of the penetrated hypha-end is as good as impos- 

 sible. Still it deserves to be mentioned here that the observa- 

 tion of the hypha-ends which had penetrated never gave 



1 See Nageli's ' Beitr. zur Wisseiisch. Botanik,' II Heft, t. i, f. 18, a. b. 



VOL. XIX. NEW SER. I 



