320 LECTURE XIII. 



are allied to the corpora amylacea, although the chemi* 

 cal tests have as yet only proved successful in the case 

 of those found in the internal ear. 



When these bodies are isolated, they exhibit in every 

 respect such a complete analogy to vegetable starch that, 

 long before I succeeded in discovering the analogy in 

 chemical reaction, Purkinje had already introduced the 

 term corpora amylacea on account of the morphological 

 resemblance. You are no doubt aware, that the chemi- 

 cal correspondence has in many quarters been doubted ; 

 the late Heinrich Meckel especially had great doubts 

 upon the subject, and supposed them to have a greater 

 affinity to cholesterine. In more recent times, however, 

 the matter has been investigated even by professed 

 botanists, and every one who has bestowed close atten- 

 tion upon it, has as yet acquired the same conviction 

 which I published as my own. Nageli pronounces these 

 bodies to be really and truly starch. 



Morphologically, they present themselves either as per- 

 fectly circular bodies with regular, concentric layers, or 

 their centre is a little on one side ; or we find twin 

 bodies ; or again the bodies are more homogeneous, pale, 

 with a dim lustre, like fatty substances. When they are 

 cautiously treated with a dilute solution of iodine, they 

 assume a pale bluish, or greyish blue colour, though a 

 great deal certainly depends upon the proper degree of 

 concentration of the test. If afterwards we very cau- 

 tiously add sulphuric acid, we obtain, when the proper 

 effect is produced, a beautiful blue, which is best shown 

 by allowing the reagent to act very slowly. When sul- 

 phuric acid acts violently upon them, a violet tint, which 

 speedily becomes brownish red or blackish, is obtained, 

 presenting a most decided contrast to the neighbouring 

 parts, which become yellow or at most yellowish brown. 



