SUBUN NATUEAL HI8T0BT SOCIETY. 47 



JANUARY, 1854. 



ON ▲ PECULIAR OBGAN IN JDSSKEA. 



Professor AUman brought forward some observations he had made on a re- 

 markable peculiarity of the adventitious roots of Jussioea grandiflora. He de> 

 scribed a remarkable condition which he had observed in some of the adventi- 

 tious roots of a specimen of this plant growing in the College Botanic Garden. 

 Some of the roots, which proceed from tne nodes of the stem, instead of growing 

 downwards, so as to fasten themselves in the mud at the bottom of the water in 

 which the plant grows, assume an ascending direction and grow into the air, 

 where they present a very remarkable appearance, looking like portions of rush- 

 pith attached to the stem of the plant. When examined by the microscope, they 

 are found to have a central, slightly developed woody axis, round which is a pe- 

 culiar structure, formed of exceedingly delicate stellate cells, having between 

 them large intercellular spaces, and constituting one of the most regular and 

 beautiful examples of a system of air-chambers to be found, perhaps, in the whole 

 vegetable kingdom. A singular fact connected with these air-chambers is that 

 they are not surrounded by any epidermal investment, but open directly into the 

 external air. Professor Allman also mentioned his discovery of a remarkable pe- 

 culiarity of the woody fibres of the same plant, namely, the fact of these fibres 

 being filled with starch granules, a condition of prosenchymatous tissue almost 

 unique in the vegetable kingdom. 



JUNE. 1853. 



ON THE CLASSIFICATION AND NOMENCLATURE OF VARIETIES OF FERNS. 

 BT J. R. KINAUAN. 



[Abridged.] 



When at the commencement of the session — (vide infra) — I submitted to 

 your Society several undescribed varieties of native ferns, I stated that before 

 the close of the session it was my intention to offer you some remarks on the 

 subject of varieties of ferns. This promise I propose now fulfilling. The 

 rough outline of the system (if I may venture to use such a term) which I mean 

 to submit to you to-night has been already laid by me before the Royal Dublin 

 Society. As I have since had opportunities of establishing what then was only 

 surmise, and of fully working out what was then but a rough outline, I hope the 



Present paper may be deemed sufficiently original to be worthy of a place in your 

 roceedings. In every work on the subject of British ferns we find species de> 

 scribed under two classes, viz. : the Ordinary Form, and what authors term Va- 

 rieties, under the latter including every departure from the original type, whe- 

 ther it be or be not permanent under cultivation, or affecting the whole plant — 

 a mere monstrosity, or a doubtful species. This system gives rise to great in- 

 conveniences, as the student is often unable to tell whether the plant so de- 

 scribed as a variety is (in relation to the original form) to be considered as a 

 form modified by climate, &c., or as a mere deviation from the normal type, aris- 

 ing from some accidental circumstance of soil, situation, &c. A second inconve- 

 nience under the present system with which students have to contend arises from 

 the want of fixity of nomenclature, authors having described these forms, even 

 in the same species, under different names, totally irrespective of those used by 

 others who have preceded them. A third inconvenience arises from authors 

 having described the same character of variety when found in different species 

 by different names, thereby burdening the student's memory with a host of 

 terms. These evils, doubtless, have in great part arisen from this subject not 

 having been studied, it bein^ the fashion with many to consider all monstrositie.s, 

 i. e. aberrant forms, as outside the pale, atid, as such, unworthy the attention 



