On the Nutrition of Musculur and Pulmonary Tissues. 349 



cene and this new body which I have found in petroleum residues 

 does not cease here. 



If this latter is exposed in hot solution in benzole to strong 

 sunlight for many hours, it deposits^ on cooling, needle-like 

 crystals which are almost colourless, and give a spectrum by 

 fluorescence which corresponds very closely with that of the so- 

 lution of the same body mentioned already. Its bands, how- 

 ever, are far less strongly marked than those of the unsolarized 

 material; and I have little doubt that, as with impure anthra- 

 cene, they are due, not to the mass of the material, but to a trace 

 of a coloured substance which is not, like chrysogen, entirely 

 decomposed by sunhght, but only so far modified as to occasion 

 the above changes. 



To avoid circumlocution in speaking of these bodies in future, 

 I would propose to call the white material petrolescene, from its 

 source, fluorescence, and general analogy to anthracene and the 

 colouring-matter which is the source of the brilliant fluores- 

 cence by which my attention was first drawn to the body 

 thallene, from the two brilliant green lines which are the most 

 prominent characteristics of its spectrum. 



I should mention that petrolescene is distinguished from an- 

 thracene by its high boiling- and melting-point (about 700" F.), 

 by its very sparing solubility in boiling alcohol and benzine, 

 and by its crystallizing in spirules and not in scales. 



Thallene diff'ers from chrysogen in its spectra of fluorescence 

 and absorption, and in its action under the influence of sunlight. 



My friend Dr. Geo. F. Barker, to whom I am indebted for 

 references to some original papers and aid in procuring a supply 

 of material, has kindly undertaken the chemical examination of 

 these bodies ; and in connexion with him I hope soon to report 

 more fully on the subject. 



I wish here also to acknowledge my obligation to Mr. W. 

 E. Geyer, my assistant, and to Messrs. P. P. Poinier and A. 

 H. G, Sorge, students in the Institute, for various assistance 

 in carrying on the observations. 



XLII. On the Nutrition of Muscular and Pulmonary Tissues in 

 Health and when affected with disease from Phthisis. By 

 William Marcet, M.D., F.R.S.^ 



Part I. On the Nutrition of Muscular Tissue in Health. 



THE object of the present memoir is to give a description 

 and an explanatory statement of the investigation I have 

 undertaken into the phenomena of the nutrition of animal tis- 

 * Communicated bv the Author. 



