1886.] 



MICROSCOPICAL JOURNAL. 



47 



hoi, and those stained in carmine, if 

 left in water, lose the color much 

 more slowly in the parenchymal than 

 in other parts. 



In my previous paper on double- 

 staining of wood, etc., I said, if the 

 blue was used before the red anilin, 

 the selection of color was reversed. 

 This is ti'ue as regards matured wood, 

 but does not hold good when stems 

 and midribs are vuider treatment. 



Matured wood is better stained by 

 the alternate methods. In longitudi- 

 nal cuts, the first color used goes to 

 longitudinal woody fibres, the sec- 

 ond to spiral vessels, ducts, and bark. 

 Sections of stems and leaves not in- 

 frequently 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 ex- 

 tremes of hard and soft tissues. 



Double stainings should be exam- 

 ined 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, N. Y., gives 

 me perfect satisfaction, while a Ger- 

 man article I have used bleaches blue 

 and green anilin stainings as though 

 it contained some alkali. 



Benzole instantly fixes those ani- 

 lins that fade in alcohol and oil of 

 cloves ; but it does not do to transfer 

 objects from alcohol to benzole, ex- 

 cept 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 in- 

 juriously upon starch and protoplasm. 

 This is not the case with dilute nitric 

 acid and chlorate of potash, nor 

 with alcohol. 



In regard to fading, an experience 

 of eighteen months enables me to 

 speak quite favorably. 



Some few leaves stained in blue 

 anilin and in h^ematoxylin fade in- 

 jiu'iously ; others lose little or no 



color. Sections double-stained in 

 green and carmine have perfectlv 

 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 colors, were more 

 generally known and availed of, the 

 studv of vegetable histology would 

 be even more attractive than at pres- 

 ent. So striking and precise is the 

 manner in which certain dyes seize 

 upon ceitain tissues, that it must be 

 seen in order to be fully appreciated. 



A word about the cutting of sec- 

 tions, for much 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 leaves 

 become crisp, which rarely occurs, 

 a few minutes residence in water 

 renders them pliable. 



In making sections of leaves, 

 longitudinal cuts of midribs may be 

 made, o r verti co-transverse cuts 

 through the midrib, including one- 

 third of an inch of leaf on either 

 side, or through several veins ; leaves 

 and small stems held against a piece 

 of potato or turnip that has been 

 hardened in alcohol may be cut 

 with a razor flat on the side, which 

 is inferior when the back is held to- 

 wards you. Alcohol should b e 

 poured over the object and razor 

 while cutting. Large stems are bet- 

 ter cut in a section machine, using 

 parafiine as an imbedding agent. 

 The object should be flooded with 

 alcohol while cutting, and the paraf- 

 fine should be trimmed to a cone- 

 shape aromid it after every two or 

 three cuts. 



A knife I use with my section cut- 

 ter acts so satisfactorily upon both 

 animal and vegetable tissues that I 

 will describe it. It weighs 7^ ounces 

 (avoirdupois). The handle is stout, 

 and is 4^ inches long, the blade is 7^ 

 inches long by 1^ inches wide, the 

 back beinsf i- inch thick. The infe- 



