HARDWICKE'S SC IENCE- GOSSIP. 



99 



Process III.— To Stain Sections in Green Aniline 

 and Carmine. 



1st. Put your section in a three-grain solution of 

 iodine-green, and let it remain for one or two hours. 



2nd. Soak in alcohol for five or ten minutes, for 

 reasons given above. 



3rd. Put in water for a minute. 



4th. In the borax carmine from thirty to forty- 

 five seconds. 



5th. Shake rapidly in water, and soak out any 

 excess of carmine that may be taken up. 



6th. Put in alcohol for five minutes. 



7th. In clean alcohol for ten minutes. 



8th. In absolute alcohol for ten minutes. 



9th. In oil of cloves for fifteen minutes. 



10th. Mount. 



Process IV. — To Stain Sections in Green Aniline 

 and Carmine Compound. 



1st. Mix fifteen drops of borax carmine with 

 fifteen drops of the three-grain iodine-green solu- 

 tion. 



2nd. Transfer section from alcohol to water for a 

 minute. 



3rd. Put in the dye from thirty to sixty seconds. 



4th. Shake rapidly in water, and soak out any 

 excess of carmine that may have been taken up. 



5th. Treat with alcohol and oil of cloves as in 

 process III. 



Ammonia carmine may be used in the same 

 proportion as the borax. Formerly, in process 

 III., I used the carmine before the green, but I 

 now follow Dr. B. W. Barton's plan of using the 

 green first, as far better results are thereby ob- 

 tained. 



To stain sections in luematoxylin and aniline-blue, 

 the mode of procedure is the same as for leaves ; 

 but they stain more rapidly, and only require the 

 dilute dye. 



Whether sectionsTare stained by^ the alternate 

 or by the compound methods, the ; selection of 

 colours is", the same. The red and green aniline 

 and the hsematoxylin go to spirals, bass cells, 

 scattered thickened cells, and, sometimes, to thick 

 epidermis and hairs. 



The blue aniline and carmine always go to 

 parenchymal and often to thin epidermic and 

 hypodermic tissues. The selection of colour in 

 matured wood is different, as will be seen further on. 



It is not possible, I think, to give a satisfactory ex- 

 planation of double staining of either animal or vege- 

 table tissues. We can only say that certain dyes seem 

 to have an affinity for certain cells. This is best 

 shown by soaking single stainings in a fluid that 

 removes their colour. If sections stained in red or 

 in green aniline be soaked in alcohol, and those 

 stained in hsematoxylin in alum-water, the colour 

 will rapidly leave the loose parenchyma, but will be 



retained for many days by the denser cells, as 

 spirals, bass, &c. 



On the other hand, specimens stained in blue 

 aniline, if left in alcohol, and those stained in 

 carmine, if left in water, lose the colour much more 

 rapidly in the parenchymal than in other parts. 



In my previous paper on double-staining of wood, 

 &c., I said, if the blue was used before the red 

 aniline, the selection of colour was reversed. This 

 is true as regards matured wood, but does not bold 

 good when stems and midribs are under treatment. 



Matured wood is better"stained by the alternate 

 methods. In longitudinal cuts, the first colour used 

 goes to longitudinal woody fibres, the second to 

 spiral vessels, ducts, and bark. Sections of stems 

 and leaves not infrequently give better results by 

 the compound methods. These results are superior 

 to those obtained in wood, for the reason, I think, 

 that in the latter there are not the same extremes 

 of hard and soft tissues. 



Double stainings should be examined by artificial 

 light. 'Compound dyes should be used immediately 

 after they are made. 



Care should be taken to obtain a good article of 

 absolute alcohol. That manufactured by Dr. E. R. 

 Squibb, of Brooklyn, U. S. A., gives me perfect 

 satisfaction, while a German article I have used 

 bleaches blue and green aniline stainings as though 

 it contained some alkali. 



Benzole instantly fixes those anilines that fade in 

 alcohol and oil of cloves ; but it; does not do to 

 transfer objects from alcohol to benzole except 

 through the medium of oil of cloves, on account of 

 the injurious contraction it causes. 



It should be borne in mind, that chlorinated soda 

 acts somewhat injuriously upon starch and proto- 

 plasm. This is not the case with dilute nitric acid 

 and chlorate of potash, nor with'alcokol. 



In regard to fading, an experience of eighteen 

 months enables me to speak quiteTavourably. 



Some few leaves stained in blue aniline and in 

 hsematoxylin fade injuriously pothers lose little or 

 no colour. Sections double-stained in green and 

 carmine have perfectly stood the .test of twelve 

 months. Those in magenta and blue as a rule hold 

 well. 



If the effects produced by staining properly- 

 prepared vegetable tissues, with one or two colours, 

 were more generally known and availed of, the 

 study of vegetable histology would be even more 

 attractive than at present. So striking and precise 

 is the manner in which certain dyes seize upon 

 certain tissues, that it must be seen in order to be 

 fully appreciated. 



A word about the cutting of sections, forjnuch 

 depends upon this preliminary step. . They must be 

 cut thin and even. 



Vegetable parts cut into pieces should be kept in 

 alcohol for a week or] two before sectioning. * If 



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