Bubbles rising through suspensions of the bacteriophages T2 and T4 and of Escherichia coli adsorb and eject these particles in droplets that are formed when the bubbles burst. The concentration of the viruses in ejected droplets, determined from electron microscopy, exceeded the suspension concentration by 50 times. Similar results were obtained for Escherichia coli. The viability of some of the adsorbed particles was established by biological counts.

TWLNTY-FIVE FIQUREHTo describe completely the morphologic changes which take place during development of a tissue a s complex as the cerebral cortex is scarcely feasible. The task calls for an analysis of the manifold changes in nucleus, cytoplasm and processes of each type of neuron in each of the several layers of the many cortical areas, as well as in the several varieties of glia. There are, however, a number of estimations which are practicable. At various stages of gestation, percentage of cortex which is nucleus or perikaryon, the number of nerve cells per unit volume of cortex, and the average volume of the nucleus and the cell body can be measured with reasonable accuracy. It is also possible to estimate the time when stratification appears in the cortex and when neuroblasts are changing rapidly to cclls with the characteristics of primitive neurons as judged by appearance of Nissl substance and elaboration of cell processes. This paper deals with the changes in these quantities in one area of the cortex of the guinea pig during the last 35

The histochemical localization of glucose-6-phosphatase activity in neonatal mouse liver was studied under electron microscopy. The activity was demonstrated in the tubular endoplasmic reticulum, which pervades the glycogen areas of the cell during glycogenolysis. Activity was also demonstrated in the nuclear envelope and ergastoplasm.

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