460 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



haemolysis. This laky blood is then added by means of sterile pipette to 

 sterile saline (1*2 p.c.) in test-tabes in the proportion of 1 to 2. The 

 setting free of the hemoglobin renders the medium most suitable for 

 the ready growth of Protozoa. 



Method for obtaining Pure Cultures from Sputum.* — It is often 

 difficult to obtain pure cultures of lung microbes from bronchitic sputum, 

 owing to the contamination of the material with organisms derived 

 from the mouth. W. E. M. Armstrong removes these adventitious 

 bacteria by placing the sputum in the wire-mesh cavity of a tea-strainer 

 and washing under a tap. The outward salivary wrappings, with the 

 microbes contained therein, are washed away. This is partly due to 

 the violence of the water stream, partly to the superior solubility of 

 the salivary portion to that of the more gelatinous bronchial part of 

 the sputum. Cultures from the bronchial part, which remains behind, 

 may be pure. 



C3) Cutting, includingr Embedding: and Microtomes. 



Bausch and Lomb's New Model Minot Automatic Precision Micro- 

 tome. f — This microtome (fig. 90) has recently been so improved as 

 virtually to be a new model. Under proper conditions it will cut 

 absolutely uniform sections down to one micron. The gearing between 



Fig. 90, 



the flywheel and crank reduces the motion in a ratio of three to one ; 

 the specimen is thus prevented from moving too rapidly against the 

 knife, and the jar upon the feeding mechanism is also avoided. It is 

 equally suitable for paraffin and celloidin preparations. The object- 

 clamp, supported on the vertical V-slide, is adjustable vertically upon it 

 and also on two planes. The feeding mechanism is controlled by an 

 adjustable cam, the impact on which is by roller, and both this and the 

 cam are of hardened steel. A great saving of time is effected by the 

 split nut and the releasing lever ; this enables the carriage to be instantly 



* Lancet (1912) i. pp. 1339-40. 



t Bausch and Lomb, Special Catalogue, 1912, pp. 8 and 9. 



