CHAPTER XII. 



STAINING AND INJECTING. 



IN many instances it is necessary to stain a preparation 

 not merely to form a pretty object let this be understood at 

 the outset ; but to show certain details of formation not 

 easily discerned in an unstained specimen. When aniline 

 blue and magenta are used for the double staining of 

 vegetable tissues, such as the section of a Burdock stem, 

 Mr. Barrett tells us the different parts are stained as 

 follows : 



Pith ;. Very pale magenta. 



Cellular tissue Deep magenta. 



Spiral vessels of medullary sheath . . Deep blue. 



Pitted vessels Blue. 



Cambium Deep blue. 



Liber cells Dark magenta. 



Laticiferous vessels Deep blue. 



Cuticle parenchyma . . Pale blue. 



Epidermis Deep blue. 



Hairs Pale magenta. 



Mr. Stiles, in a paper to 'The Northern Microscopist,' 

 makes the following remarks upon this subject : 



Stems of all kinds should, if possible, be cut when fresh. 

 If they cannot be obtained in this state, they may, previous 

 to cutting, be soaked in cold or tepid water, or in a mixture 

 of equal volumes of spirit of wine, glycerine, and water. 

 Fresh stems or roots can be preserved in this medium for 

 almost any length of time, and will remain in excellent 

 condition for the section machine. 



Logwood Staining. Wood sections require bleaching 



S 2 



