178 NATURAL HISTORY SOCIETY OP DUBLIN. 



the dark spots were occasioned by insects ; but after repeated attempts, 

 I did not succeed in again rinding spirals. It is, however, desired to 

 record this occurrence of spirals, and Mr. Archer has very kindly made 

 a sketch of them, which accompanies this paper (Plate II., .Figs. 7, 8, 

 9, 10). I have always taken the greatest pains to perfectly clean the 

 glasses I use in microscopic examinations, and I do not believe any error 

 has been occasioned by neglect of this necessary precaution; but as I failed 

 in my attempt to find these spiral vessels a second time, I think it prudent 

 merely to record their occurrence. 



Admiral Jones exhibited the original specimen of JEvernia prunastri, 

 bearing the black dots, within the substance of one of which he had 

 found the remarkable spiral vessels forming the subject of the present 

 communication. 



Dr. David Moore, P. L. S., considered the Society should feel itself 

 much indebted to Admiral Jones for making it the medium by which he 

 made public so remarkable an observation. He had himself seen the 

 specimen, and believed that not only did the sketch convey a correct 

 representation of what he had seen, but that the vascular tissue must 

 have truly belonged to the lichen, and was not that of some higher 

 plant which had intruded from some other source during the manipula- 

 tion. Spiral cells have been found in certain fungi, and analogy would 

 possibly lead one to expect their being met with belonging to a lichen. 

 He thought that some of the cells he had seen in the preparation shown 

 to him by Admiral Jones presented somewhat of a " scalariform" appear- 

 ance ; and this present record, especially if hereafter confirmed, would be 

 extremely valuable. 



Mr. Archer, who had to thank Admiral Jones for having kindly 

 afforded him an early opportunity to examine the singular preparation 

 obtained from the lichen in question, believed that the drawings thereof 

 which he had endeavoured to make conveyed at least a correct idea of 

 the vascular bundles themselves thus found in a plant so unexpected. 

 He did not consider these " vessels" were any of them " scalariform," or 

 " annular," but were strictly " spiral." After examining the specimen 

 very carefully, he was in very few instances able to see the ends of these 

 spiral vessels, owing to their being, without injuring the preparation, so 

 inextricably immersed in the brown cellular mass, mixed with fragments 

 of coarse pellucid fibres, which together seemed to form the substance or 

 tissue producing the dark dots apparent on the surface of the lichen, and 

 which had first attracted Admiral Jones's attention. Mr. Archer stated, 

 however, that where he had been able to see the extremities of the vessels, 

 he had found that they gradually tapered ; and he drew attention to one 

 instance depicted in the sketch, in which one had been broken off by the 

 pressure, and the fibre uncoiled — thus proving its strictly spiral cha- 

 racter (see Plate II., Pig. 9). These vessels, indeed, by mutual contact, 

 sometimes acquired somewhat flattened surfaces for a considerable 

 length, and the fibres, following the angles thus produced, assumed 



