The relation of the laboratory to the practice of medicine is a topic which has been abundantly discussed in the recent journals. In our modern hospitals the clinical laboratory is considered indispensable; here, urine analysis, blood counts, serum reactions and bacteriological diagnosis are daily occurrences. Our journals are filled with reports of microscopic investigation; many of these articles are "preliminary" and our memory may leave us doubtful whether further examination has confirmed or denied these bids for precedence.
One of the most enticing of these laboratory studies is the examination of the blood. The beautiful proven results furnished the profession from time to time, and, still more, the brilliant promises of what may be expected in the future make the subject of absorbing interest to the scientific physician of to-day. This holds true, whatever his specialty may be. Many lesions of the eye are found to be explainable only by