228 SUMMARY OF QUERENT RESEARCHES RELATING TO 



work recently accomplished by Professor A. E. Wright. This relates to 

 the employment of the Microscope as a part of the physician's equip- 

 ment in the ordinary work of treating such diseases as arise from 

 microbic invasion. It is well known that nature's remedy for such 

 diseases is found in the activity of a certain type of white blood cor- 

 puscle, itself a microbe of a very militant order, which voraciously 

 devours the smaller microbes of the morbid kinds. It is found, however, 

 that this phagocyte is not always on the alert, and Professor Wright's 

 investigations have led him to the conclusion that the secret of the 

 phagocyte's activity is to be sought in the composition of the blood 

 serum. He has, accordingly, devised a system of measurement for the 

 stimulating property of the blood fluids. A minute sample of the 

 patient's blood furnishes the required specimen of serum, and to this 

 serum is added a pure culture of the noxious bacterium. This mixture 

 being placed in an incubator, a certain number of phagocytes are let 

 loose, and allowed to play in it for a regulated period of time. A sample 

 of the mixture is then withdrawn and examined under a Microscope, 

 and some 50 or 60 specimen phagocytes are taken, from which an average 

 is deduced of the amount of execution which the phagocyte can do in 

 that medium. If the result of that examination is satisfactory, then the 

 patient's blood is in such a condition that inoculation treatment can be 

 successfully applied. If, however, the phagocytes prove not to be very 

 keen in seizing and appropriating their destined prey, then the system 

 of treatment has to be directed to improving the condition of the 

 patient's blood before commencing the inoculation treatment. A photo- 

 graph of a phagocyte with ingested tubercle bacilli, enabled the audience 

 to appreciate the precision of this method. 



The Microscope adapted to Special Duty.* — In his second lecture 

 Mr. Gordon referred first to a topic which, under pressure of time, was 

 omitted from the previous lecture, that is to say, the limit of visibility. 

 This subject has been much under discussion in recent times, and Lord 

 Rayleigh has of late investigated it with very remarkable results. It 

 now appears that objects such as a bacterium or that minute appendage 

 called a flagellum, which many bacteria carry, may be seen although 

 attenuated much beyond the point hitherto commonly supposed to be 

 the inferior limit of microscopic vision. The importance of this fact 

 lies in the circumstance that many bacteria are so minute that it is 

 difficult to make out their distinctive features, and the study of these 

 delicate but vitally important forms of life, taxes our present Microscopes 

 to the limit of their capacity. 



The lecturer next demonstrated by means of a Microscope, lent for 

 the purpose by Mr. C. Baker, the appliances which are employed in the 

 metallographer's Microscope to illuminate the surface of an opaque object 

 such as a polished slab of metal, describing particularly the construction 

 of the vertical illuminator and the method of focusing adopted under 

 these conditions. He then passed to consider modifications directed to 

 improving the resolving power of the instrument, and showed by a very 

 striking experiment how a thin film of some transparent body, such as 



* Lectures at the Royal Institution, Feb. 1906. 



