Common. Wild fowl are most abundant 

 throughout Macedonia, and had I made a 

 longer stay in the country, no doubt many 

 other species would have been observed be- 

 sides those mentioned. 



Mr. G. II. K. Thwaites on the Cell-Membrane of Plants. 15 



Anser ruficollis. Only one of these very rare birds was observed. 



Cygnus musicus. Very common. 



Anas tadorna. 



A. boschas. 



A. strepera. 



A. acuta. 



A. penelope. 



A. crecca. 



A. clypeata. 



A. nyroca. 



A.ferina. 



A. clangula. 



Mergus serrator. Common. 



M. albellus. Very numerous, though none but females were ob- 

 served ; the same remark applies to the Ionian Islands. Might not 

 some of these supposed females have been males, not having assumed 

 the breeding plumage ? 



Pelecanus onocrotalus. Very eommon. 



Carbo cormoranus. 



C. graculus. 



C. pygmaxts. Most numerous. 



> Common. 



III. — Observations on the Cell-Membrane of Plants. 

 By G. H. K. Thwaites*. 



If a decaying vegetable organism is brought before us, in wilich 

 nothing remains of the former structure but the cell-walls, it is 

 difficult to conceive that this skeleton, as it were, has performed 

 an important part in the vital processes of the plant, — that it has 

 been an agent in the chemical changes which had been going on 

 during the processes of secretion, assimilation, &c, — in fact, that 

 it has been any other than a mere skeleton for the support of the 

 important parts of the organism : I say that, divesting the mind 

 of preconceived notions respecting the functions of cell-mem- 

 brane, it is difficult to regard it, under such circumstances, other- 

 wise than in the light I have just mentioned. I hope to be able 

 to show that this is really the view which should be taken of it. 



To prevent any misconception of my meaning, I will just state 

 that when using the term " endochrome " in the succeeding part 

 of my paper, I wish it to be considered as comprising the entire 

 contents of the cell, including the nucleus or nuclei. The terms 

 cell-membrane or cell-wall explain themselves. 



There cannot be a more satisfactory way of showing the sub- 

 ordinate character of the cell-membrane than by exhibiting a 

 perfect living organism in which it does not exist, and there are 



* Being the substance of a paper read at I Meeting of the Bristol Micro- 

 scopical Society, April b, 1810. 



