The preceding paper by Rittenberg, together with the number of articles on the same subject which have appeared recently, indicate an ever increasing interest on the part of biologists in the atmosphere as a medium for the dispersal of bacteria, molds, spores and pollens. Meteorologists, on the other hand, are interested in the results of such biological investigation to the extent that they show certain mixing processes within the atmosphere and the movements of air masses. In view of the large quantity of data which has already been accumulated by the biologists, it becomes of considerable interest to consider some of the results from the standpoint of fluid mechanics.