Abstract

ABSTRACT In 1895 Hamburger described a remarkable phenomenon which can be observed in suspensions of mammalian red cells in isotonic, hypotonic, or hypertonic saline and in sugar solutions, but not in serum or plasma. The normally biconcave discoidal cells become perfect spheres, without undergoing any apparent alteration in volume; the addition of serum to the suspension of spherical cells, however, converts the spheres back again into the typical discoidal form. Hamburger has no explanation to offer for the occurrence of this phenomenon, but suggests that it may be due to changes in surface tension. In 1920 Brinkman and van Dam published a study of the phenomenon, in which they record the changes undergone by the red cells of man and of the rabbit when placed in a haemocytometer chamber. They correct Hamburger’s statement in one important respect, for they observe that red cells in saline are not spherical but discoidal, and that they become spherical only when placed in the haemocyto-meter chamber. In becoming spheres they pass through an intermediate form, “the crab-apple form,” which is spherical but finely crenated. Brinkman and van Dam believe that the cause of the phenomenon is that the cells receive an electrostatic charge from the glass when they come into contact with the floor of the chamber. They confirm Hamburger’s statement that the change from disc to sphere is prevented by the presence of serum, and claim that it is the cholesterol contained in the serum which inhibits the change of form. Unaware of these two investigations, Gough in 1924 described the same phenomenon once gain, but fell into Hamburger’s error of believing that the red cells are spherical when suspended in a volume of saline. This error is very easy to make, and both Millar and I have made it also; indeed, as will be seen below, it is impossible to avoid it if an oil immersion objective is used for examining the cells. Gough adds two interesting observations to the previous descriptions: that ammonium oxalate and ammonium chloride act like serum in preventing the cells from becoming spherical in saline, and that the spherical form becomes crenated after a few hours, passing spontaneously into the discoidal form in about 24 hours. He does not give any detailed explanation of the phenomenon. Both Millar and myself (Millar 1925, Ponder 1925) made the same mistake as Gough and Hamburger, in believing that the spherical form is due to the immersion of the cells in saline and that cells are spherical when freely suspended in this medium. On such an assumption, I carried out many measurements of sedimentation velocity without receiving any indication that the assumption was wrong1. It appears, however, on a more detailed examination, that the essential condition under which the spherical form occurs has escaped all the observers who have worked on the subject, and that the phenomenon is much more complex than has hitherto been believed.

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