496 



and observations which have been published concerning it. He 

 alluded especially to the accounts given by Leuwenhoek, Baker, and 

 Ehrenberg, and next noticed the discussions concerning its nature 

 which have been carried on by Siebold and Eckhard. But what was 

 more particularly the subject of the paper, was the Memoir lately pub- 

 lished by Professor Williamson, of Manchester. According to the 

 observations of this observer, the Volvox is a confervaceous plant, and 

 the animalcules described by Ehrenberg are merely the endochromes 

 of the several cells, reduced to a small bulk by the secretion (between 

 the outer cell walls and the internal cell membrane) of a hyaline sub- 

 stance. The cilia described by Ehrenberg, as belonging to the indi- 

 vidual animalcules are, according to Mr. W., really attached to the 

 external covering of the organism. Mr. Williamson also proposes the 

 theory that the production of the young Volvoces, consists more of a 

 process of growth than reproduction, and refers the true reproductive 

 functions to certain bright granules, which are contained imbedded in 

 the endochrome of each cell, these being the spores of the plant. 

 Mr. S. stated, that though in the main, the observations of Mr. 

 Williamson appeared to him to be correct, and that many of his de- 

 ductions appeared legitimate, still there were some points in the 

 Memoir with which he could not agree. With regard to the parts 

 from which the cilia are developed, Mr. S. thinks that the various facts 

 concerning them with which we are acquainted, rather lead us to the 

 belief that they are really developed from and properly belong to the 

 cell membranes immediately enclosing the endochromes of the cells. 

 Next, as regards the organs of reproduction or spores, he could not 

 agree with Mr. Williamson in thinking that the bright granules were 

 the spores ; he thought it seemed much more likely, and that it was 

 borne out by analogy, to suppose that the whole masses of endochrome 

 were the spores; and this, he said, seemed more probable if we re- 

 gard the cilia as being attached thereto. The author next entered 

 into the question as to the animal or vegetable character of the Volvox ; 

 and after examining the arguments which might be brought forward 

 to support either theory, he came to the conclusion that the organism 

 should, without hesitation, be referred to the vegetable kingdom. The 

 communication was illustrated with very beautiful diagrams, kindly 

 supplied by Professor Balfour. 



The reading of Mr. Sibbald's paper gave rise to a short discussion, 

 in which Professor Balfour and Mr. Wyville Thomson took part. 



4. ' On the Development of the Sporidia and Spores of Lecanora 

 tartarea;' by Wyville T. C. Thomson, Esq. The author gave a 



