1. A slit sampler for air-borne bacteria is described, in which air is sucked through a narrow slit on to the surface of agar in an ordinary Petri dish.2. This method has proved very rapid and simple in use, and has appeared more efficient than other methods against which it has been tested.3. The collection efficiency for an aerosol consisting of Staph. albus, sprayed from distilled water as single cocci, is about 96%. The method thus collects the finest bacteria-carrying, particles almost as efficiently as coarser ones.4. In contrast to this, the exposure of plain open Petri dishes appears to collect the larger particles in the air of crowded rooms at least 200 times as efficiently as it does single washed bacteria. This highly selective effect renders it advisable to use great caution in evaluating tests made in plain open dishes.5. The methods of determining sampling efficiency, and their errors are discussed in detail.

The work described below has been done in an attempt to isolate vitamin D from the complex mixture formed by the ultra-violet irradiation of ergosterol. It is evident that vacuum distillation might be of use for this purpose, but, except for a brief statement by Windaus and Holtz (1927), we are unaware of previous work on the distillation of vitamin D.We have distilled various products obtained from ergosterol, and most frequently have used resinous products prepared as follows. A solution of ergosterol in ether was exposed to the unfiltered radiation from a mercury vapour lamp while flowing through a narrow silica tube at a rate such that about 40 per cent, of the ergosterol was destroyed. The unchanged ergosterol was then removed by precipitation with digitonin as described in a previous paper (Webster and Bourdillon, 1928) and the ethereal solution of the products of radiation was evaporated in vacuo to a dry resin. Construction of Still.

No abstract

No abstract

Illustrative Cases Case 1.-A lance-corporal was admitted with a history of injury to the right arm sustained by a fall while engaged in physical training. Clinically he showed a gross angtilation deformity of the mid-shaft of the right humerus, with shortening of one apd a half inches. Dorsiflexion of the wrist was not possible. One attempt at reduction had been made before admission. Treatment was carried out by the method described. At eight weeks clinic'al unin 'was sound, with steady improvement of the injury to the musculo-spiral nerve.Case 2.-A soldier was admitted giving a history of injury to the left arm sustained in a motor-cycle accident. Clinically he showed a fracture of the mid-shaft of the left humerus, with the lower end of the upper fragment palpable anteriorly and with 3/4 inch shortening. There was no evidence of musculo-spiral involvemnent. One attempt at reduction was made before admission and one in hospital by a colleague. Treatment was carried out by the method described, except that a brachial block was used. At seven weeks clinical union was sound, and a radiograph showed good callus formation. (11 ft. 6 in. by 7 ft. 6 in. by 9 ft. 3 in. high) contained a table, two wooden chairs, and heating-pipes. The floor and table were oiled to keep down dust, the door and window were kept shut so far as was possible, and the air in the room was circulated, partly by convection from the hot-water pipes, but chiefly by a 12-inch electric ' table" fan pointing upwards at 45 degrees from one corner of the floor and running at about half-speed. The air was sampled through two glass ,tubes (diameter 1 inch) leading from points about 1 ft. 6 in. above the table through one of the walls