Progress of Rational Pathology. 235 



chronic and exsudative inflammation of the choroid as the 

 cause of glaucoma : the exsudation is deposited between the 

 choroid and the retina, and displaces the latter : thence the 

 amblyopia. Sichel explains the green colour of glaucoma, by 

 supposing that the bluish choroid is seen, through the lens 

 and vitreous body, deprived of its pigment. The crystalline 

 lens is reproduced (according to Pauli, Lowenhardt, Textor 

 and Valentin) in animals, and in man after the operation for 

 cataract : the new formed substance resembles exactly the 

 normal*. 



q. Skin. — According to Rosenbaum, cutaneous eruptions 

 are diseases of the glands of the skin, especially of the hair 

 follicles : but papulae and pustules occur on parts of the cutis 

 and on mucous surfaces, where neither hair nor hair follicles 

 occur (as on the palm of the hand, the glands, and the con- 

 junctiva) many papular eruptions, such as lichen, psosiaris, &c. 

 do no doubt proceed from the hair follicles. 



II. — Miasmatico-contagious Diseases. 



Of late years two chief theories regarding contagion have 

 been advocated. The one seeks to explain the action of 

 infectious matter (like that of ferment) by its chemical and 

 physical properties. The other (the parasitic theory) regards 

 the infectious matter as an organic existence, having an in- 

 dependent life of its own, with the power of propagating it. 



Chemical theory. — This rests on the principle " of the 

 transposition of atoms by being shaken/' In certain bodies 

 the molecules are supposed to be kept together so very 



* The general result of the numerous experiments, which have been made in the 

 transplantation of the cornea from the eye of one animal to that of another, appears 

 to be this— that there is not much difficulty in getting the transplanted cornea to 

 become attached in its new position, and that in a few rare cases the cornea re- 

 mains transparent for a day or two, but that in the end it always becomes opaque, 

 or quite useless for vision. A recent writer on this subject in Dr. Finch's Journal, 

 does not appear to be aware that this operation was practised on the human subject, 

 at least seven years ago.-— Tr. 



