82 *HIS TOL OGY OF NUTRIENT FL UIDS. 



Uraemia may occur from any disease of the kidneys which ob- 

 structs the secretion of urine. 



6. Ammonccmia. Retention of urine and septic inflamma- 

 tion of the bladder ma}- lead to urinary decomposition and the 

 formation of ammonia, which passes into the blood, exhibit- 

 ing its presence by fever, vomiting, strong ammoniacal breath, 

 and chronic catarrh of the intestines. 



7. Hydrothioncemia, or sulphuretted hydrogen in the blood, 

 produces its poisonous effects of general collapse, and the 

 urine gives to acetate of lead paper the reaction of the gas. 



8. Chylcemia, or molecules of fat in blood, may occur after 

 a meal of fatty materials. In larger drops lipaemia fat may 

 be found in diabetic blood, and after injuries. 



9. Accidental products. Air, fatty degenerated epithelial 

 cells, bits of detached valves of the heart, emboit or portions 

 of thombi, and calcareous plates from the aorta, may also be 

 found in the blood. 



10. Parasites are living organisms inhabiting other living 

 organisms from which they derive their nutriment. 



a. Plants. I. The schizomycetes or bacteria play the most 

 important part in pathology. Many are innocuous, but others, 

 by their great multiplication, or by abstracting nutriment or 

 oxygen from the tissues, or by the irritation of their poisonous 

 products, cause many forms of disease, both of structure and 

 function. As the serum of the blood is an excellent germicide, 

 bacteria are rarely found in it, although they or their spores 

 may be conveyed by the blood vessels or lymphatics to inter- 

 nal organs, where they multiply. The details of bacteriology 

 form an extensive study, but our present purpose will be served 

 by reference to the principal forms of pathogenic bacteria. 

 The microscopic forms or appearance are by no means sufficient 

 to distinguish disease-producing species from those which are 

 innocent. For this purpose it is necessary to cultivate the 

 bacteria on artificial media, and reproduce the disease by in- 

 jecting the culture into another animal. Such procedure in- 

 volves great care and skill in laboratory experiments. It is 

 generally necessary to stain the specimen and examine with 

 oil-immersion lenses in connection with an achromatic or Abbe 



