Alan Boyden

Precipitin Tests as a Basis for a Quantitative Phylogeny

In an earlier report 1 the results of a series of precipitin tests on the sera of certain common Mammalia were given. The degree of reaction as indicated by the titer of the ring tests was expressed as percent of the homologous titers. A new method of using these percent values as a basis for a quantitative phylogeny is here proposed and illustrated. The method involves the calculation of the average values of the reciprocal relationships between pairs of species. These average values (M) constitute the primary data to be used. The values of M together with their probable errors are given in Table I. The least reliable value (dog vs. horse) is still 3.3 times its P.E., and hence the whole series is probably significant. To express these quantitative measures of relationship graphically, it is proposed to use the corresponding 100-M values for the actual distances between the loci of the species. For example, taking dog as the starting point, the distances of the other species from dog are given in the table. The positions of the other species, beef, sheep, pig and horse may then be further defined by their corresponding 100-M values in relation to each other. There will be four 100-M values to be used in establishing the proper locus of each species and all must be so used. The result is shown in Fig. 1, which gives a side view of the spatial arrangement of the loci projected on a plane surface. It should be borne in mind that Fig. 1 shows only the present relationships of these 5 species, not their ancestry. The figure does not show time and hence cannot show ancestry. To add the element of time to this geometric figure would require a fourth dimension.

Gravity Shock in Rabbits. I. Lack of Correlation Between Plasma Protein and Specific Gravity.

The calculation of protein concentration from the specific gravity of human and dog serum or plasma 1 , 2 has been widely used in clinical and experimental laboratories especially since the development of the falling drop method for measuring specific gravity, 3 , 4 because it is quicker than analyses by the Kjeldahl method. It is important to know how the serum or plasma protein concentration changes in traumatic, hemorrhagic, and other kinds of shock, as well as in other pathological conditions, and much reliance has been placed on specific gravity determinations on the blood of such subjects.5 In order to determine whether the same relationship between specific gravity and portein concetration exists in rabbit plasma as in human and dog plasma, blood from 20 normal rabbits fed on Purina chow and later from the same animals suspended by their ears until the became unconsious from peripheral circulatory deficiency (“gravity shock”) 6 has been studied. The plasma of arterial heart blood was analyzed for protein by the micro-Kjeldahl method, for glucose by the Folin-Wu method as modified by Andes and Northup, 7 and the specific gravity was determined by the falling drop method. In Fig. 1 plasma protein before and during gravity shock is plotted against plasma specific gravity. The data for normal animals are well described by the line drawn through the open circles having the equation: P = 375 (Gp −1.0064), which is of the same order of magnitude as the equation reported for human 1 and dog 2 plasma. For rabbits in gravity shock, however, the constant relation between specific gravity and protein concentration did not hold, as indicated by the solid circles, showing even greater divergencies than those found by Moore and Van Slyke 1 in human nephritic patients.