INVEKTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 931 



characters for species in licliens, and tlie development of fast dyes 

 from licliens cai^able of competing witli the coal-tar and other recent 

 products of the chemist's laboratory. 



During the last twenty-five years the principal changes in our 

 knowledge of the chemistry of these colouring matters consist in 



(1) the addition of sundry (supposed or really) new substances, con- 

 fusing to a still greater degree the previous confusion of names ; and 



(2) certain proofs of the correctness of the opinion, that several, at 

 least, of the bodies described by different chemists as differing 

 trivially in constitution are referable to the same substance. A new 

 series of conjoint researches by competent chemists and licheno- 

 logists are therefore required. Not only are neio fields of research 

 open, but the need of a revision of all previous analyses is even more 

 evident. Chemists themselves are forced to make this admission, but 

 the subject has not as yet proved a sufficient counter-attraction to the 

 innumerable other interesting problems daily exposed for solution in 

 organic chemistry. Meanwhile, the crude researches of lichenologists 

 may serve to pave the way for the subsequent more scientific and 

 precise analyses of chemists, by indicating the directions in which 

 chemical inquiry is likely to prove useful or successful. 



The foregoing along with other considerations have induced 

 Dr. Lindsay to submit the results of another more systematic and 

 complete series of experiments, supplementary to those presented in 

 1853-5. These results include a general inquiry into colour- 

 development in the whole family of lichens, and the experiments are 

 on the one hand a repetition, and on the other an extension, of the 

 former series, and illustrate generally the colour-reactions of lichens. 



A solution of the lichen colorific principles was used in hot 

 water or alcohol, boiling the lichens, previously reduced to powder 

 or minute fragments, as the majority, at least, of the colouring 

 principles, while insoluble in cold and sparingly so in hot water, are 

 readily soluble in cold or boiling alcohol. The reactions developed 

 are thus the efiects of reagents on the alcoholic or aqueous decoctions of 

 the lichen-thallus. 



Whilst the specimens experimented on were for the most part 

 comparatively old, a parallel series of experiments was made on fresh 

 lichens in their own places of growth with, on the whole, similar 

 results. 



Dr. Lindsay has prepared a voluminous series of elaborate tables 

 of details of his experiments which is not however yet published. 



Microgonidia.* — Dr. J. Miiller, of Geneva, replies to the objections 

 brought forward by de Bary, and reasserts the correctness of the 

 discovery by Dr. Minks of the " microgonidia " of lichens ; which he 

 states have now been detected also by nearly all the Geneva botanists ; 

 by Dr. Tuckermann, of Amherst, and by Herr Stodder, of Dorten, 

 without any chemical preparation, and by ToUes' immersion-systems 

 (h Td5 iV' ^^^ irV)- For the observation of the " microgonidia," 

 Dr. Miiller recommends immersion objectives, with Abbe's condenser, 

 and an illumination of white light only reflected from white clouds, &c. 

 * ' Flora," Ixii. (1879) p. 294. 



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