On some Applications of Osmic Acid. By T. J. Parker. 383 



terminal bud of Chara ; and for this I have found it so successful, 

 that I have no doubt of its usefulness for other structures of a like 

 nature. The buds were placed in acid until they appeared black, 

 and were then treated with alcohol as described above. They were 

 then clarified with oil of cloves, and imbedded in cacao butter, and 

 the sections cut were mounted in balsam. The method is extremely 

 good for the younger parts of the bud, such as the apical cell, smallest 

 leaves, &c. ; but the oil of cloves and balsam cause a good deal 

 of shrinking of the older cells: it might possibly be better to 

 imbed in glycerine jelly, and to mount the section in glycerine. 

 The staining of these objects is very successful; the acid seems 

 to have been taken up by each granule of the protoplasm, and 

 there to have been decomposed, giving the granule the characteristic 

 grey colour. A mixture of osmic and chromic acids (chromic acid, 

 • 25 p. c, 9 parts ; osmic acid, 1 p. c, 1 part) answers, in some 

 respects, even better than osmic acid alone for this purpose. 



In this, as in all the former instances, one great advantage of 

 the method is that hardening and staining are performed in one 

 operation. 



