Malaria : etiology, pathology, diagnosis, prophylaxis, and treatment / by Graham E. Henson.

  • Henson, Graham E. (Graham Edward), 1874-
Date:
1913
Catalogue details

Licence: In copyright

Credit: Malaria : etiology, pathology, diagnosis, prophylaxis, and treatment / by Graham E. Henson. Source: Wellcome Collection.

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    ETK )L( )G V—OTHER FACTORS. grow considerably before they die and we have occasionally seen small rings attain over half the full adult size under these circumstances. When para- sites die in these deep cells the central clear space in the small ring closes, or if the parasite is older the irregular projections, pseudopodia, are with- drawn. If pigment is present, it loses its motility. The protoplasm gradu- ally shrinks, losing its staining reaction, and finally only the nuclear chro- matin granule remains, and this also stains poorly. In the instance of very small parasites often the red blood cell shows little or no evidence of the previous presence of the parasite. rlhe parasites in the thin layer at the top of the column of cells develop and may lie examined at any time by drawing a small quantity of cells from this layer by means of a capillary pipette. Some considerable practice is required in order to do this without drawing cells and dead parasites from just below this layer. The pipette may be passed through a flame to sterilize it on the outside, but it must be allowed to cool thoroughly before it is used, since, in our experience, a temperature of 45° to 50° C. kills the para- sites in a very short time. Such a temperature also alters the red blood cells in some way so that they are rendered permeable to the surrounding serum, and this effect is destructive to the parasites. Great care must be taken in handling tubes containing cultures to keep them in the upright position. Tilting to the side results in burying and killing the living parasites in the thin layer at the top of the cells which have settled to the bottom of the tube. Technic for (Cultivating More than One (feneration.—If more than one generation of plasmodia is to be cultivated, it is necessary to remove the leucocytes when the culture is made in order to avoid destruction of the parasites by them at the time of segmentation. The infected blood from the patient is centrifugalized sufficiently to force the leucocytes to the surface of the cells. The length of time necessary to centrifugalize varies with the speed, length of arm, etc., of the particular centrifuge used and should be determined by experiment. Unnecessary centrifugalization should be avoided. rl he supernatant serum is drawn off and put in culture tubes. The column of serum in each should be one-half to one inch deep. Cells and plasmodia are carefully drawn from about the middle of the centrifugalized cells and planted at the bottom of the serum in the culture tubes. Flat bottom tubes are an advantage. One to two-tenths of a cubic centimeter of cells in a half-inch tube make the thickest layer in which it is possible to get a. homo- geneous growth of parasites. We have been able to secure growth of all the parasites in about twice this quantity of cells in a half-inch tube by em- ploying tubes with a paper shelf suspended in them. They are filled with serum to at least half an inch above the level of the support for the paper disk. The disk is then carefully tucked in place, after which the cells are placed on it. We have obtained even more satisfactory results with tubes filled one-half inch deep, or more, with freshly prepared human plasma. These are con- veniently prepared by placing one-half to one inch of blood, immediately after it is drawn, in culture tubes and centrifugalizing to throw the cells hn the bottom before coagulation takes place. By continuing centrifugaliza-