PLASTIDS 



196 



PLEUROPNEUMONIA 



chloroplastids containing chlorophyll 

 or chromoplastids containing other pig- 

 ments. Chlorophyll thus segregated 

 in these bodies acted on by light plays 

 its part in starch production, as hemo- 

 globin (erythroplastids) acts in trans- 

 port of oxygen. The chloroplastids are 

 easily visible microscopically. Special 

 techniques are only required to reveal 

 the organization of the ground sub- 

 stance, holding the chlorophyll, and 

 their rdles in photosj^nthesis. A full 

 account is provided by Guilliermond, 

 A., The Cytoplasm of the Plant Cell. 

 Waltham: Chronica Botanica Co., 1941, 

 247 pp. (translated from the French by 

 L. R. Atkinson). 

 Platelet Counts. Total counts can be made 

 in plasma. Walker and Sweeney (T. F. 

 and P. A., J. Lab. & Clin. Med., 1939, 

 25, 103-104) proceed as follows : Moisten 

 inside white blood cell pipette by draw- 

 ing in and expelling 1.1% aq. sodium 

 oxalate. Immediately draw in fresh 

 blood to 0.5 mark, then oxalate solution 

 to mark 11. Shake vigorously. Place 

 heavy rubber band around pipette to 

 close ends. Centrifuge pipette § min. 

 at 1,600 revolutions, or the shortest time 

 to draw red blood cells into its stem. 

 Stand pipette vertically to permit red 

 blood cells to settle into stem (about 2 

 hrs.). Gently expell red blood cells by 

 blowing and count platelets in clear 

 supernatant solution. 



Another method (Buckman, T. E. 

 and Hallisey, J. E., J.A.M.A., 1921, 

 76, 427-429) is to prick the finger, or 

 ear, through a drop of 0.1% brilliant 

 cresyl blue in physiological saline. The 

 fluid, plus blood is mounted and the num- 

 ber per red cell is counted. If there 

 is one platelet per 20 reds and there 

 are 6 million reds per c. mm., then there 

 are approximately 300,000 platelets per 

 c. mm. of blood which is a normal count. 

 The number may exceed 1 million in 

 myelogenous leukemia. 



A choice can be made from many 

 platelet staining solutions: (1) Buck- 

 man, T. E., and Hallisey, J. E., J.A.M. 

 A., 1921, 76, 427: Glucose, 6.0 gm.; 

 sodium citrate, 0.4 gm.; aq. dest., 100 

 cc. Filter, add 0.02 gm. toluene red 

 (dimethyldiamidotoluphenazin ) then 

 0.1 gm. crystal violet. Heat gently to 

 60°C. 5 min.; cool and centrifuge at 

 2000 revolutions per min. for 10 min. 

 Filter supernant fluid twice through 2 

 thicknesses fdter paper. Preserve solu- 

 tion by adding 0.2 cc. formaldehyde. 

 (2) Kristenson, A., Acta Med. Scan- 

 dinav., 1922, 57, 301: Urea, 10 gm.; 

 sodium citrate, 2.5 gm.; corrosive sub- 

 limate, 0.005 gm. ; brilliant cresyl blue, 

 0.5 gm.; and aq. dest., 500 cc. (3) 

 Ottenberg, R, and Rosenthal, N., J.A. 



M.A., 1917, 69, 999: 3% aq. sodium 

 citrate to which 1:500 cresyl blue or 

 1 :500 methyl violet is added and filtered 

 before staining. (4) Pratt, J. H., J.A. 

 M.A., 1905, 45, 1999: Sodium citrate, 

 3.8 gm. ; aq. dest., 100 cc. ; formaldehyde, 

 0.2 cc; brilliant cresyl blue 0.1 gm. 

 (5) Wright, J. H. and Kinnicutt, R., 

 J.A.M.A., 1911, 56, 1457: A. Brilliant 

 cresyl blue, 1 gm.; aq. dest., 300 cc. 

 B. Potassium cyanide, 1 gm.; aq. dest., 

 1400 cc. Keep A in ice box. For use 2 

 parts of A and 3 parts of B are mixed and 

 filtered. 



A differential platelet count, in which 

 4 classes are recognized, is described by 

 Olef (I., Arch. Int. Med., 1936, 57, 

 1163). 



Platelets. These can best be seen in the 

 dark field in mounts of fresh blood and 

 of fresh blood first treated with Anti- 

 coagulants." The contrast between the 

 two is instructive. It is important to 

 remember that when held under ob- 

 servation in preparations sealed with 

 vaseline for a considerable time, plate- 

 lets may become elongated and exhibit 

 a superficial resemblance to parasites. 

 Data on the rate of disintegration of 

 platelets are provided by Olef, I., J. 

 Lab. & Clin. Med., 1936-37, 22, 128- 

 146. In blood regeneration atypical 

 platelets may be encountered measur- 

 ing as much as 25-50 m in length (Tocan- 

 tins, M., Medicine, 1938, 17, 175-258). 

 The contained granules are easily 

 stained supravitally and in smears. 

 Excellent coloration of platelets in sec- 

 tions are given by Wrights and Kings- 

 ley's methods (see Megakaryocytes). 



Platino-Acetic-Osmic mixture, see Her- 

 mann's Fluid. 



Platinum. Intravenous injections of col- 

 loidal solutions of platinum in rabbits 

 are described by Duhamel, B. G., C. 

 rend. Soc. de Biol., 1919, 82, 724-726. 



Platinum Chloride is the name usually given 

 to hydro-chloroplatinic acid. It is used 

 occasionally as an ingredient of fixa- 

 tives. 



Platyhelminthes is the phylum of flatworms. 

 The two classes of important parasites 

 are the Cestodes and Trematodes. 

 See Parasites. 



Pleuropneumonia. Staining of organisms. 

 Stain paraffin sections 4 microns thick 

 of tissue fixed in Zenker, Bouin, abso- 

 lute alcohol or Carnoy's fluid brought 

 down to water directly in Mallory's 

 phosphotungstic acid hematoxylin (18- 

 24 hrs.) without preliminary treatment 

 with permanganate and oxalic acid. 

 Do not wash but blot nearly dry and 

 dehydrate rapidly in absolute alcohol, 

 clear in xylol and mount in balsam. 

 Organisms in lungs appear as deep blue 

 masses of mycelial threads (Turner, H. 



