ON PLANT TISSUES. 157 



sium. Hence we have plants which entirely refuse any reaction ; 

 others in which it is feeble, and becoming decided by the addition 

 of another chemical ; others, again, in which the Molybdate acts 

 vigorously alone. In a few instances, there seems to be a dif- 

 ference in colouration between the upper and the lower epiderm. 



We have, during many years past, been employing aniline dyes 

 to tinge vegetal cells, and have at length succeeded in obtaining a 

 triple or multiple staining of the cells of some plants. Yet these 

 results, to my mind, are not of the nature of a true chemical 

 reaction in cell-contents, but rather a staining effect upon the cell- 

 walls; the cell-contents appearing to have been done away with in 

 the process of preparation. 



As the results obtained by the use of the Molybdate are varied, 

 so in measure we obtain some differentiation; f6r, in some in- 

 stances, only some cells appear to be acted on, the others either 

 refusing to react, or doing so very slowly. 



Further, the chlorophyll appears in some cases to have under- 

 gone some process of disintegration, these being full of fine yellow 

 molecular matter, which often exhibits molecular or swarming 

 motion for a time. 



The colouration in some cases appears to be affected by the 

 addition of alcohol, used for the purpose of dehydrating the spe- 

 cimen, but, on the whole, it is permanent, and will bear to be 

 mounted in Canada Balsam. When mounted in Glycerine jelly, 

 some of these specimens make fine objects for examination, the 

 vascular tissue between the cells taking colour. Still, these speci- 

 mens do not come up to the beauty and elegance of a neatly 

 coloured aniline preparation — red and green, etc. 



I have now experimented on over 120 different plants, employ- 

 ing various parts, such as portions of the stem, leaf-structure, 

 hairs, petals, and seeds, with varying results ; and I am in hopes 

 this mode of chemical examination may lead to some definite 

 results, when the experiments have embraced several hundred 

 kinds of plants. To the physiological botanist this process will 

 prove interesting if not useful, for the effect, when fully obtained, 

 presents variations which are very pleasing ; and inasmuch as the 

 specimens can be readily prepared, there will be, I think, a great 

 advantage in making a fair collection of such objects. I am 



