190 MANUAL OF HISTOLOGY. 



regular intervals, a rather scanty proportion of cells, either quite spherical 

 or spheroidal, which may take on other distorted forms, however, owing 

 to their soft consistence and the semi-fluid nature of the surrounding 

 medium. They resemble enlarged colourless lymph oid cells, &c., and 

 are granular, either coarsely or finely so, but usually to no great extent, 

 so that they are not very opaque. Their membrane opposes a certain 

 amount of resistance to the action of acetic acid, and the nucleus appears 

 more or less granular, showing in its interior a nucleolus. We also meet 

 with round, oval, reniform, and double nuclei, which have always their 

 special nucleoli, indicating probably a multiplication of cells here. 



The size ofthese cells is 0-0104, 0-0156-0-0182 mm., while the simple 



nuclei have an average diameter of 

 0-0052 mm. 



Fusiform and stellate cells are 

 not entirely absent in the true 

 corpus vitreum, but are found 

 principally in the membrana hya- 

 loidea in connection with the for- 

 mation of the vessels of that part, 



Fig. 180. Structure of vitreous humour in a four as Kolliker j UStlv observes. 



The same is found to be the struc- 

 ture of the vitreous humour of the infant, while, according to the general 

 opinion, the cells undergo decay in the first years of childhood, so that 

 in adults the corpus vitreum is composed of the intercellular substance 

 alone; a view which is opposed by 0. Weber. According to this 

 observer, namely, the cells of the mucoid substance remain in all cases, 

 though more scanty towards the centre than at the periphery. 



Examined chemically by JBerzelius, Lohmei/er, and Virchow, the corpus 

 vitreum was found to contain more than 98*5 per cent, of water, and 

 among the solid constituents an abundance of inorganic matter, chiefly 

 made up of chloride of sodium. Among the organic matters we find 

 traces of albumen. According to Virchow a substance allied to mucus is 

 also to be found here, to which the semi-fluid gelatinous nature of the 

 structure is due. The vitreous humour is now regarded as composed of 

 a certain quantity of mucin gelatinised in a large amount of saline fluid. 

 The following analysis by Lohmeyer is given for the purpose of showing 

 more clearly the composition of the substance in question. 



1000 parts of vitreous humour contain : 



Water, ._.'.' 986 "400 



Membranes, . . . . . . . 0'210 



Albuminate of sodium (and mucin ?) . . 1*360 



Fats, . -. ".; . ' . . . . 0-016 



Extractives, 3*208 



Chloride of sodium, ..... 7 -757 



Chloride of potassium, ..... 0'605 



Sulphate of potassium, . . . . . 0'148 



Phosphate of calcium, . . . . . O'lOl 



Phosphate of magnesium, .... 0'032 



Phosphate of iron, 0'026 



Lime earths, 0-133 



Mucin was not looked for, but urea was found by Millon and Wolder, 

 but not by Lohmeyer. 



