88 REPORT — 1856. 



cum sativum. Prof. Henslow then exhibited Centaurea nigrescens, in which it was 

 seen that cultivated specimens of seedling plants had completely passed into the 

 form of C. nigra. He then referred to instances of species of Rosa, Primula, and 

 Anagallis, passing one into the other. 



On the Movements of Oscillatoria. By Professor G. B. Knowles, F.L.S., 

 Queen's College, Birmingham. 



The OscillatorijE belong to a group of plants which seem to stand immediately 

 between the animal and vegetable kingdoms. After very careful and repeated exa- 

 minations, the author has fully satisfied himself that the motions of this family of 

 freshwater Algae are entirely independent of any electrical influence ; of any current 

 in the fluid in which they are placed ; or of any effort to recover their straight posi- 

 tion. The motions, in fact, have very much the appearance of being spontaneous ; 

 an opinion in which Prof. Knowles is pleased to find that Captain Carmichael, who 

 devoted his attention for many years to the investigation of marine and freshwater 

 algae, fully concurs. 



Many of the larger Oscillatoriae, if carefully watched, may be seen to move in 

 various directions, sometimes to the right, sometimes to the left ; sometimes slowly, 

 sometimes briskly. The author, however, never perceived in them anything like an 

 effort to recover the straight position which is considered to be natural to them. 

 On the contrary, they may often be observed to hend gradually, so as to form a very 

 considerable curve ; to return again to the straight position, and then to hend in an 

 opposite direction. They have also a progressive motion ; and two filaments lying 

 side by side, may frequently be seen advancing in opposite directions on the field of 

 the microscope. This progressive motion, in all probability, is effected by means of 

 cilia, although they have not hitherto been detected. Of the correctness of these 

 facts any one may readily convince himself, by examining with a little attention 

 fresh specimens of any of the larger Oscillatoriae. 



On the genus Abrothallus, De Nrs. By W. Lauder Lindsay, M.B., Perth. 



The genus Abrothallus has long been misunderstood and little known by botanists. 

 Its species have generally been regarded either as the abortive, monstrous or acces- 

 sory apothecia of various common lichens : — as parasitic species of Endocarpon or 

 Lecidea ; or as parasitic Fungi. They are athalline : hence the apothecia, which 

 are very minute, almost microscopic, may be said to constitute the plants. They 

 are parasitic on the thallus of various common foliaceous lichens belonging to the 

 genera Parmeliu, Cetraria and Sticta ; and are esi)ecially abundant on furfuraceous 

 states of Parmelia saxatilis. Though comparatively unknown to British botanists. 

 Dr. L. has met with them plentifully on old road-side walls, and more sparingly on 

 boulders, rocks, and trees, both in the Highlands and Lowlands of Scotland ; and 

 more particularly in the neighbourhood of Perth, Dui.keld, Braemar, Glen Shee, 

 Lochaber, Skve, and Dumfries. The genus is specially interesting, from possessing, 

 in addition to the ordinary reproductive organs, — the spores and sperraatia,- — of 

 other lichens, accessory, leproductive bodies, siylospores, contained in minute 

 microscopic conceptacles, termed by Tulasne Pycniod^s. The presence of stylo- 

 spores and the absence of a tballus, tend to assimilate this genus closely to the 

 Fungi, between which and the lichens the marks of differentiation are daily beco- 

 ming less and less distinct. 



The first approach to a satisfactory examination and description of the genus was 

 made by De Notaris, who, however, was led into various eirors regarding its struc- 

 ture. He described it as possessing a small, delicate thallus ; hence the name 

 which he bestowed on the genus. This thallus is now ascertained to belong to, or 

 to be a modified portion or anamorphosis of, the ihuWus of Parmelia saxaiilis, or 

 other lichen, on which the Ahrolhallvs is parasitic. His errors were corrected by 

 Tulasne, in a monograph cm the genus Jbrot/tallun, and certain allied parasitic 

 genera, included in his elaborate and valuable memoir on the minute anatomy of 

 the lichens, published in the 'Annales des Sciences Naturelles' for 1852. The 

 results of Dr. Lindsay's examination of a large number of Scotch specimens, have 



