HARDWICKE'S SCIENCE- GO SSIP. 



97 



DECOLOURING AND STAINING VEGETABLE TISSUE 

 FOE MICROSCOPICAL EXAMINATION. 



By GEORGE D. BEATTY, M.D. | 



previous occa- 

 sions I have con- 

 tributed to this 

 journal articles on 

 decolouring and 

 staining vegetable 

 tissue. Experience 

 gained during the 

 past year enables 

 me to give jn this 

 article processes that will produce 

 improved results. 



All vegetable sections, and some 

 leaves, may be prepared for stain- 

 ing by soaking them in alcohol, or 

 in a mixture of dilute nitric acid 

 and chlorate cf potash ; but I 

 much prefer the results obtained 

 by first bleaching them in "Labar- 

 raque's Solution of Chlorinated Soda," and then 

 treating them -with alcohol for a few hours. 1 In half 

 an ounce of the soda solution a large number of 

 sections may be placed, but not more than a dozen 

 half or one-inch leaves, or parts of large leaves cut 

 into inch pieces. Leaves in greater number adhere 

 to each other, aud thereby take longer to bleach. 



Sections of matured wood should be kept in this 

 solution from twelve to eighteen hours ; sections of 

 stems, leaves, and petals from six to eighteen hours ; 

 pistils and stamens, and sections through the gynse- 

 cium and receptacle of flowers, from two to six hours. 

 Leaves and petals should not only be bleached by 

 the Labarraque, but should also be rendered trans- 

 lucent. This is accomplished in from six hours to 

 six days. 



•If delicate leaves show evidence of disintegration 

 after they are bleached, but before they have become 

 translucent, they should be removed to alcohol, 

 after washing! them in water as described below. 

 This renders them translucent within two days. 

 No. 137. 



After removing from the Labarraque, put them 

 into half a pint of clear water. Change the water 

 five times during twenty-four hours, acidulating 

 the third washing with five or ten drops of nitric 

 acid. Sections can be washed in half the time 

 required for leaves. 



Next, put into alcohol, which in a few hours 

 prepares them for staining. 



In alcohol, tissue may be kept for months without 

 turning yellow. 



I.— Staining Leaves and Petals. 



For staining leaves and petals the best dyes are 

 aniline-blue and haematoxylin. 



Other anilines than the blue may be used, but 

 they are not so pleasant to the eye, and are harder 

 to work, as they fade out in both alcohol and oil of 

 cloves. 



Red aniline may be used one quarter of a grain 

 to an ounce of alcohol; violet, one half-grain ; and 

 green, three grains. 



To make the blue aniline dye, dissolve in a mortar 

 half a grain "of " Nicholson's Soluble Blue Pure" in 

 one ounce of 90—93 per cent, alcohol, which has been 

 acidulated with half a drop of nitric acid ; then filter. 



Dilute a portion of this with alcohol to obtain a 

 quarter-grain solution. 



The formula for the hsematoxylin dye is given 

 further on. 



A bright purple dye, good for leaves and sections, 

 is made by steeping fresh berries of the Phytolacca 

 decandra in alcohol. The stainings are quite per- 

 manent, but the dye does not keep over six weeks. 



To Stain Leaves and Petals in Aniline blue. 



1st. Transfer several small leaves from alcohol to 

 about half a drachm of the quarter-grain blue. 



If not stained of sufficient depth of hue in one 

 hour — 



2nd. Transfer to the half-grain blue for a quarter 

 or half-hour. 



F 



