42 On Medical Science: [ Jan., 
within his reach; that of the saccharine is almost within it; but 
the albuminous is still beyond.”* 
The application of such researches as these to the Science of 
Medicine is too obvious to need pointing out. They furnish the 
only safe basis on which the knowledge of diseased actions and of 
morbid poisons can be founded. To the latter class of bodies, 
owing to the unusual prevalence of infectious diseases, special 
attention has recently been paid, and we seem to be on the eve of 
brilliant discoveries in reference to some of them. The question is 
still unsolved whether the poison, or contagiwm, of the so-called 
Zymoses, consists of living germs, 7.e. entire, although undeveloped, 
organisms, or of living portions of organic matters, 7.e. germinal 
particles or cells, or of dead matter, peculiarly compounded, and 
undergoing some special process of decomposition. 
For a further extension of our power of research into the 
chemical constitution of organic bodies, we are indebted to a new 
application of the Science of Optics. Spectrum analysis now not 
only tells us of what elements the planets and the photosphere of 
the sun are composed, but whether certain red spots which may be 
the subject of medico-legal inquiry, are or are not stains of blood. 
For this great discovery we have to thank Mr. Sorby, of Sheffield. 
Dr. Bird Herapath, of Bristol, was the first to employ it in the 
inquiry into a case of alleged murder. It is impossible in imagina- 
tion to limit the extent to which micro-spectroscopy may aid us in 
the analysis of organic bodies. 
One of the latest applications of physical science to the purposes 
of medicine is a further extension of the powers of sight. Endo- 
scopy, in its various forms, by most ingenious combinations of lenses, 
mirrors, tubes, and, in some instances, increased means of illumina- 
tion, enables us now to explore all the canals opening on the surface 
of the body, and even to inspect some of its cavities. The revelations 
thus made are wonderful, and have far exceeded the expectations of 
those who first suggested such means of research. It might have 
been expected that, looking through the window of the Cornea, we 
might ascertain the exact condition of the internal structures of 
the eyeball. But who would have imagined that from the morbid 
changes observed in them we might be able to pronounce with 
certainty on the existence and nature of disease existing, not only in 
the brain, but in so remote an organ as the kidney? An amusing 
instance of the enthusiasm with which this line of inquiry is now 
pursued was given at the international medical congress which 
recently sat in Paris. A zealous worker in the field of endoscopy 
foretold the time when, by means of the lime-light, the whole body 
* Dr. Letheby’s Introductory Lecture at the London Hospital._— British 
Medical Journal, Oct. 5, 1867. 
