THE TRICHOMYCETES 629 



anemia, blackwater, &c. They are found in the true secreting cells 

 Hning the first portion of the convoluted tubules of the kidney. 

 Rarelv the three kinds may be found in the same cell. 



To show the three Pigments: — 



Stain with carmine ten minutes. 



Stain with acid alcohol three minutes. 



Stain with potassium ferrocyanide five minutes. 



Stain with acid alcohol until blue. 



Treat with spirits, oil of cloves, xylol and mount. 



This is a chemical process, and Prussian blue is formed. 



The potassium ferrocyanide and acid alcohol can be repeated 

 several times until the part is sufficiently blue. 



The pigment in the lung is chiefly carbon ; treat the section with 

 an alkali if suspicious, carbon will not be dissolved, but melanin will. 



The pigment in the skin of the dark races is not like that of malarial 

 pigment. It contains no iron whatever, and is dissolved in weak acids, 

 which distinguishes it from true melanin. Tattoo pigment is deposited 

 very irregularly, and can be diagnosed at once under the microscope. 



Between bacteria proper (Schizomycetes) and the moulds (Hypho- 

 mycetes) comes a group known as — 



THE TRICHOMYCETES. 



This group is divided into : — 

 The leptothrix, no branching. 

 The cladothrix, false branching. 

 The streptothrix, true branching. 



The Actinomyces. 



This ray fungus is a streptothrix consisting of filaments, cocci and 

 clubs. The filaments are long and thin, interlacing in the centre of 

 the colony forming a network. In older filaments the protoplasm is 

 broken up into coccoid bodies which may break out from the sheath. 

 The clubs are involution forms perhaps produced by resistance of the 

 tissues. 



In actinomyces from human tissues : — 



The threads are Gram-positive, the clubs Gram-negative, but from 

 cattle the threads are Gram-negative and the clubs are Gram-positive. 



Man may be injected with the bovine type. In artificial media the 

 clubs are not found. Il grows well on potato and glycerine agar. 



On potato it forms a thick, grey, raised, wrinkled growth of sulphur 

 yellow or light chocolate colour. 



It causes actinomvcnsis in man and cattle. 



