352 Botanical Society of Edinburgh. 



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. 



The .author stated, that though in the main the observations of 

 Mr. Williamson appeared to him to be correct, and that many of his 

 deductions seemed 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, he 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 regard 

 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 argu- 

 ments 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. 



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

 tartarea," by Wyville T. C. Thomson, Esq. The author gave a 

 sketch of the structure of Lichens in general and of their mode of 

 nutrition and reproduction. He considered spores as being the ulti- 

 mate germinating cellules, the product of the division of the compound 

 granular cell which is the result of the union of the conjugating cells 

 in cryptogamic plants ; sporidia as the compound granular cells, the 

 product of the union of conjugating cells ; proto-sporidia as the simple 

 cells of lichens in which the two conjugating cells are afterwards 

 formed ; gonidia as free cellules derived from and part of the cellular 

 tissue of the parent plant, capable of continuing to a certain extent 

 their development when free from the parent, without the interven- 

 tion of the true generative act of conjugation (the analogues of free 

 buds or bulbils in Phanerogams). Mr. Thomson also considered 

 the pro-embryo in Ferns and other Cryptogams as the cellular expan- 

 sion formed by the development of the gonidium, and containing the 

 conjugating cells. This pro-embryo, then, corresponds to the ordinary 

 cellular expansion of Lichens. 



The author then examined the structure of Lecanora tartarea, a 

 crustaceous lichen holding a middle place between the foliaceous and 

 the pulverulent species : — 



" When we examine a section of the frond of Lecanora tartarea, 

 we meet, in the layer which immediately adheres to the rock or bark, 

 chosen for its place of growth, with a mass of elongated, more or less 

 filiform cells. Most of these cells are empty — some of them contain 

 a slightly viscid fluid, and in a few there appears to be an undeveloped 

 nucleus ; the cells are delicate and of a light gray colour. Resting 

 immediately above these, and sometimes struggling down among them, 

 are groups of rounded cells filled with bright-coloured chlorophyll, 



