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abundance during the summer and autumn, but not during the winter. This fact, however, lost some of its significance in consequence of the further dis- covery of the presence of embryos in the worms from other pastures at all times of the year. So far as the enquiry has extended, it may for the present'be assumed that strongles deposit eggs in the bronchial tubes and lung tissue ; that the embryos are fully formed and often hatched in the lungs, and are expelled in the act of coughing ; falling on the pasture, they are swallowed by earthworms, in which they undergo certain changes, Avhich fit them for residence'in the system of the mammalia. At this stage the embryo is cast out by the earthworms, and eaten by grazing animals. Some of the young worms will find their way into the larynx and down the trachea into the bronchial tubes. Others will most probably ascend the nasal chambers, and enter the wind pipe that way. Those which get into the digestive system cannot be, or at least have not been, traced any further ; but if they do not remain and adapt themselves to their new surroundings by such changes of form as may be necessary, they must be either expelled or digested. It is quite certain that typical lung strongles are not found in the digestive organs. SEVERAL VARIETIES of strongles are found in the lungs of cattle and sheep. In the calf the most common is the Strongylus micrurus, a short-tailed strongle. In the sheep the Strongylus filaria, a thread-like strongle, is more often found. Two nematodes are also seen in the lungs of sheep the Strongylus rufescens, and the worm which has recently been described as the Pseudalius ovis, a long thread-like worm which is found coiled up beneath the pleura in small cavities, or inclosed in little masses of calcareous matter. Strongylus rufescens is distinguished from the Strongylus filaria by its small size, and red or yellow tint. It is sometimes found in association with the filarise in the bronchial