A new single-control micromanipulator.

SEVERAL types of micromanipulator have been described (for reviews see Peterfi, 1928; Chambers and Kopac, 1937; Seifriz, 1936). The growing importance of micrurgical techniques in bacteriology, electrophysiology, embryology, plant physiology, and experimental cytology have focused attention on the problem of micromanipulator design. The question has assumed a new importance with the recent development of two revolutionary advances in microscopy. The first of these is the high-performance reflecting microscope of Dr. C. R. Burch (see Burch, 1947; Barer, 1948a). The instrument in use at Oxford has a working distance of 13 mm. when used at N.A. 0-65. This long working distance is exceptionally useful for microdissection, as it enables the usual type of moist chamber and hanging drop preparation to be dispensed with. It is now also possible to perform micromanipulation on the surfaces of intact organs in situ, e.g. the liver, spleen, kidney, or brain of anaesthetized animals (Barer, unpublished results). The second outstanding advance in microscopy has been Zernike's phase-contrast method (Zernike, 1942; Burch and Stock, 1942; Barer, 1947&, 19486). This enables living unstained cells to be studied under optical conditions vastly superior to those hitherto available. There is no doubt that much early work will now have to be repeated and extended by the use of this method. The technique of microdissection by phase-contrast illumination is far from easy, but the results amply repay the trouble.