Abstract
Although the advantages of continuous agitation in phagocytosis experiments had been noted by earlier investigators, 1 , 2 , 3 Robertson and Sia 4 were apparently the first to use the rotatory-oscillation method extensively. All have observed that constant mixing during incubation promotes bactericidal action and produces more constant results than stationary incubation or intermittent agitation. Most of the previous work has been done with cultures of pneumococci and we were faced with the necessity of checking these factors with the streptococcus with which we were working.
An agitating machine utilizing the same principle as that in the machine used by Fenn 2 and later in the improved machine of Robertson and Sia 4 was designed and built for us by Mr. Wm. H. Hamilton, E. E. It consists of 3 brass flanges mounted rigidly on a motor driven shaft. Two of the flanges act as tube holders, having 5/8 in. perforations bored at uniform intervals near the periphery, while the third flange acts as a guard. The flanges will hold 18 tubes at one time and the angle of the tubes can be altered by placing one end of the tube in the second or third perforation from that opposite the one containing the other end of the tube. The tubes are held in place by a rubber band which encircles them. A constant speed electric fan motor furnishes the power which is transmitted by pulley through a short belt (rubber band) and a worm and circular gear.
The rotating rack revolves at a constant speed of 18 r.p.m. and the mixtures shift from the base of the tube to the top against a paraffined rubber stopper and back again during each revolution. The chief advantages of this design are the mechanical simplicity, constant speed and small space occupied by the machine.
Get full access to this article
View all access options for this article.