sex of Chaetocladium was grown with either sex of Parasitella, both species acted as host to the other parasite and galls were produced characteristic of both Parasitella and Chaetocladium. The parasitic behavior of Chaetocladium has been described in detail by Burgeff.2

In a recent paper t it has been proposed that the total work involved in the circulation of blood in a section of artery (sufficiently small so that the pulsating changes in the kinetic energy of the blood stream in it can be neglected as compared to the work required to overcome friction) can be expressed by the equation:wr 4 which embodies Poiseuille's law of flow and a term which covers the cost of maintenance of blood volume, p is the fall in pressure in dynes/cm. ~, b is the cost of blood volume in ergs/cc, sec. (considered constant), vol is the volume, r is the radius of the section of artery, and 71 is the viscosity of whole blood (also taken as "constant"). At constant flow, f (that is, for any given steady state), and at constant length of arterial section, l, the total energy, E, is a minimum when:Substituting forj ~ in the original equation, we obtain:Or, to avoid constants, we may use a different unit for E, and write:(kZ)/t = r~ (4)

No abstract

When a tree, at a point where the circumference is Co, divides into two branches (cl and ct), what relationship exists between co and cl + c~? In order to answer this question, which has a definite bearing on problems of tree form, it is convenient to investigate first the relationship between the circumference at some point and the weight, w, of all the parts of the tree peripheral to this point.Accordingly measurements were made, 116 in all, on nine kinds of trees; namely, aspen, bitternut, hickory, oak, ash, maple, cedar, hornbeam, and beech. The largest tree measured had a circumference of 56.4 cm. where cut, and the whole tree weighed 120 kg. The smallest measurements were made on the stems of leaves,--for example, circumference of stem = 0.25 cm., weight of leaf = 0.18 gm. All the data thus obtained are included in Fig. 1.Our procedure was of the simplest character. Whole trees of varying size, or branches, or leaves, were taken entirely at random from the vicinity. The only criterion of selection was that the specimen should not appear to have been recently injured. The circumference was measured by a tape, encircling the bark, at the point of section; or, for small specimens, the diameter was measured by calipers and the circumference subsequently calculated. The specimen was then weighed on one of three balances according to size. The season was midsummer, 1926; the place, Grindstone Island, N. Y.Plotting logarithms; i.e., log (weight in gin.) vs. log (circumference in cm.), the points fall close to a straight line. A statistical treatment yields the following numerical characteristics:Mean value of log c in the observations =-O. 161 " " " l o g w " " " ~ 1.250

What is reported in the following pages is an example of work achieved in a relatively short time by the co-operation of a sufficient number of institutions and individuals. The venue of this research was in the Andes, and the work was carried out in the winter 1921-1922, yet its organisation only commenced definitely in the early summer of 1921, when a group of British and American physiologists secured the support of the various universities or other institutions to which they were attached. This support was given in the most ungrudging way. It included the liberation from immediate duty of the members of the party, often at considerable inconvenience to those who remained at home, the loan of apparatus, the contribution of substantial funds, and a great body of goodwill, which was perpetually translating itself into increased efficiency of the work actually accomplished. The following collaborated in one or more of the ways indicated above:— The Department of Physical Chemistry of Harvard University. The Proctor Fund of Harvard University. The Elizabeth Thompson Fund. The Rockefeller Institute of Medical Research, New York City. Columbia University.—From a fund, to which contributions were made by Dr. Walter B. James, Mr. Cleveland H. Dodge, and a contributor who wishes to withhold his name, but to whom thanks are none the less due. The Royal Society of London. The Research Grant to the Physiological Department of the University of Toronto. The Moray Fund, Edinburgh. The Carnegie Fund, Edinburgh. Sir Robert Hadfield, Bart., F. R. S. Sir Peter Mackie, Bart.