588 A MANUAL OF BACTERIOLOGY 



fixative two parts of saturated aqueous mercuric chloride solu- 

 tion, one part of alcohol, with a few drops of glacial acetic. They 

 remain in this for ten minutes. 



(b) Wash in weak spirit and then in weak spirit coloured with 

 iodine, and finally wash in distilled water. 



(c) Treat with 4 per cent, iron -alum solution for six to ten 

 hours. 



(d) Stain in Heidenhain's hsematoxylin for at least six hours. 



(e) Differentiate in 1 per cent, iron-alum, watching micro- 

 scopically. 



(/) Wash well in tap-water, pass through alcohol and xylol, and 

 mount. 



Allusion may here be made to the Mycetozoa (Myxomycetes). 

 These are masses of protoplasm resembling huge amoebae, which 

 are found on decaying vegetable matter. By some they are 

 regarded as vegetable, by others as animal, in nature, and belong- 

 ing to the Amcebce of the Sarkodina. 1 Some important plant 

 diseases, such as the " finger-and-toe " of cabbage roots, are 

 due to their activity. The finger-and-toe disease is due to an 

 amoeboid parasite (Plasmodiophora brassicce, by some included 

 among the Amcebce), the cycle of which begins with spores from 

 which small flagellulse are set free. Similar organisms have been 

 supposed to be present in cancer. 



Class II. Infusoria (Ciliata) 



The Infusoria are protozoa the locomotive organs of which 

 consist of cilia, and in which the nuclear apparatus is differentiated 

 into a vegetative macronucleus and a generative micronucleus. 

 The cytoplasm is enclosed within a cuticle, an oral aperture is 

 present in the form of a slit or pore, and waste matter is extruded 

 by a pore, constant in position, but, as a rule, visible only when 

 in use. A contractile vacuole is generally present. Reproduction 

 usually takes place by fission, which is preceded by division of 

 the two nuclei, the micronucleus by mitosis, the macronucleus by 

 direct division. 



The Infusoria are not of much pathological importance, but are 

 common in ponds and ditches, e.g. Paramecium and Vorticella. 



1 See Lankester's Treatise on Zoology, Pt. 1, First Fascicle, p. 37. 



