PARAFUCHSIN 



261 



PARASITES 



orientation of fairly large objects a 

 beam of light passed through the paraffin 

 block from an arc lamp or other powerful 

 source is of great assistance. For very- 

 minute objects a method described by 

 Fry (H. J., Anat. Rec, 1927, 34, 245- 

 252) is suggested. For refractory tis- 

 sues, like yolk laden eggs, McClung (p. 

 40) suggests hydration. The block is 

 trimmed until the imbedded tissue is 

 exposed when it is soaked in water for 

 several hours. This reduces friability 

 and brittleness and good sections may 

 often be obtained. 



Temperature and humidity are factors 

 in securing a good ribbon by making one 

 section stick evenly to the next in series. 

 Sometimes a little boiling water near at 

 hand will help but it should not be 

 necessary if the tissue has been properly 

 infiltrated with paraffin of the right 

 melting point which set firmly when 

 cooled. Static electricity, causing the 

 ribbon to adhere in a troublesome way 

 to surfaces, is partly dependent upon 

 difference in density of tissue and paraf- 

 fin. But the most important factor in 

 obtaining excellent sections is have the 

 microtome in good working order and 

 the knife sharp (see Sharpening). 

 Lillie (p. 44) says that ribboning con- 

 sistency of paraffin is sometimes im- 

 proved by adding to the paraffin before 

 infiltration 10-20% of beeswax or 3-5% 

 of halowax. For ordinary purposes 

 sections should be cut 6 microns thick. 

 To mount them on slides first smear 

 carefully cleaned slides (see Slides) with 

 Albumen-Glycerin, cover with aq. dest. 

 and gently heat over an alcohol lamp 

 if a slide warmer is not available. Then 

 mark the slides with a diamond point 

 pencil and leave for about 6 hrs. in a 

 drying oven at 40-45°C. 



Parafuchsin, see Pararosanilin (Magenta O). 



Paraganglion, see Aortic. 



Paraldehyde is paracetaldehyde, a polymer 

 of acetaldehyde employed in Dioxan 

 fixative and in other ways. 



Paraloidin, see Celloidin. 



Paramagenta, see Pararosanilin (Magenta 

 O). 



Paramylum, a form of carbohydrate store in 

 lower plants (Taylor in McClung, p. 

 221). 



Paramoecia. Directions for using dyes for 

 intravitam staining of food vacuoles, 

 contractile vacuoles and various other 

 structures, as well as minimum concen- 

 tration for effective staining and toxic- 

 ity, are supplied by McClung, 1950, 

 pp. 437-439. 



Paraplasm is a term supposed to include non- 

 living cellular components such as gly- 

 cogen and lipid granules. It is mis- 

 leading because all cellular components 



contribute in one way or another to 

 vital phenomena. Deutoplasm is syn- 

 onymous. 



Pararosanilin (Magenta O) (CI, 676) — basic 

 rubin, parafuchsin and paramagenta — 

 This is triamino - triphenyl - methane 

 chloride, the chief component of most 

 Basic Fuchsins. 



Parasites. These range all the way from 

 ultramicroscopic viruses to organisms a 

 yard or more long. Microscopic tech- 

 niques for viruses are given under Cyto- 

 plasmic Inclusions, Elementary Bodies, 

 and Nuclear Inclusions. Certain Gram 

 negative intracellular insect or arachnid 

 transmitted bacteria - like microor- 

 ganisms are called Rickettsia and re- 

 quire special methods for their demon- 

 stration. See also Bacteria and Spiro- 

 chaetales, Fungi, Piroplasma and Pro- 

 tozoa. A search for such small para- 

 sites involves not only an examination 

 of tissues but also of body fluids includ- 

 ing Blood, Feces, Gastric Contents, 

 Urinary Sediment, etc. When the para- 

 sites are scarce resort is made to methods 

 of Concentration. Elementary orienta- 

 tion in respect to the larger animal para- 

 sites (metazoa) is provided by the fol- 

 lowing classification (according to 

 Stiles) from Stitt (p. 387) which has 

 been slightly modified. 



1 . Body more or less dorsiventrally flattened 3 



Body in cross section ordinarily round 2 



2. Body never annulated, without legs or jawB.. . . 4 

 Body annulated (at least possesses mouth parts), 



breathes usually through tracheal system, 

 adults with jointed legs or other appendages.. 6 



3. Intestine present without anus, 1 or 2 suckers, 



body not segmented. (In liver, lungs, blood, 

 intestine rarely elsewhere — flukes) Trematoda 



Intestine absent, 2 or 4 suckers on head, body 

 of adults segmented, tissue usually contains 

 calcareous bodies, adults (tapeworms) in in- 

 testine, larvae (bladder worms) elsewhere 



Cestoda 



Intestine and anus present, sucker on posterior 

 end, body annulated like earthworm, in upper 

 air passagei or externally (leeches, blood 

 suckers) Hirudinea 



4. Intestine absent, armed rostellum present, very 



rare in human intestine, thorn headed worm* 



Acanthocephala 

 Intestine present, but no armed rostellum 



Nematoda 5 



5. Intestine rudimentary in adults, no lateral 



chords, rare in human intestine (hair snakes or 



horse hair worms) Gordiacea 



Intestine present with lateral chords, common 

 in intestine, muscles, lymphatics, etc. (round 

 worms) Eunematoda 



6. Six legs in adult, wings in most species, larvae 



annulated, breathe by trachea, adults ecto- 

 parasites, occasionally under skin, in wounds, 

 intestine or bladder (insects) Insecta 



