CHAP. XI.] PERIPHERAL NERVOUS END-ORGANS. 451 



upon the ground-substance of the cornea, like that of hyaline cartilage, 

 as composed of collagenous and mucin-yielding bodies. 



When digested in sulphuric acid the cornea may be split up into 

 lamellae, whilst potassium permanganate separates these into fibrils 

 which are broader than those of the fibrillar connective tissue (Kiihne). 



Acetic acid first renders the cornea transparent and afterwards 

 causes it to swell, though the ground-substance does not dissolve. 

 After digestion in dilute mineral acids, the ground-substance of the 

 cornea becomes readily soluble in boiling water. 



When the cornea is heated to 55 C. it becomes opaque, in con- 

 sequence partly of changes in the corpuscles: in part, however, because 

 of the coagulation of proteids previously existing in solution in the 

 parenchymatous fluid bathing the tissue (Kiihne) 1 . By treating the 

 cornea with water, this liquid dissolves alkaline albuminates and a 

 globulin which, according to Schmidt, possesses fibrinoplastic activity. 



Presence of ^ n tne C01irse f h* 8 beautiful studies on the 



Myosin in the histological structure of the yet living cornea corpuscles 



protoplasm of Kiihne x was led, from the eminently contractile character 



of their bodies, from their behaviour to stimuli, and from 



the changes which they undergo at death, to surmise 



the close relationship of their protoplasm to the substance of muscle. 



This relationship, according to Bruns 2 , is further evidenced by the 



fact that the cornea contains myosin, doubtless derived from its 



corpuscles. 



To obtain myosin, Bruns separated tlie cornea from the sclerotic, and 

 placed the finely divided structure in saturated solution of ISTaCl for 24 

 hours. The solution on being treated with large quantities of distilled 

 water deposited a precipitate, soluble in weak solutions of NaCl (containing 

 less than 10 per cent.) and in water containing 1 part in 1000 of hydro- 

 chloric acid. 



Results of The following is an analysis of the cornea by 



analyses of His. 

 cornea. 



Water in 1000 parts .... 758'3 

 Collagen ... . 203'8 



Organic matters insoluble in water . 28'4 



Soluble salts ... . 8'4 



Insoluble . . 



lOOO'O 



Sclerotic. 



No special information is possessed in reference to the sclerotic, 

 which, however, consists of collagenous connective tissue. 



1 Ktthne, Untersuchungen uber das Protoplasma. See section entitled "Das Proto- 

 plasma der Zellen in der Cornea " (p. 123131). 



2 Bruns, " Chemische Untersuchungen uber die Hornhaut des Auges." Hoppe- 

 Seyler's Untersuchungen, p. 260. 



292 



