268 SCIENCE PROGRESS 



brought out some striking results, investing Arneth's leucocyte 

 count with a usefulness in the diagnosis and prognosis of pul- 

 monary tuberculosis hitherto insufficiently recognised. 



The behaviour of the nuclei of the leucocytes to the effects 

 of toxaemias in the production of laevodeviation is explained by 

 Arneth on the views which he holds on the origin, development, 

 and life-cycle of these cells. According to his hypothesis the 

 neutrophile leucocytes are developed from the myelocytes of 

 the bone marrow. At their origin they possess an undivided 

 nucleus. Later the nucleus divides and continues to divide so 

 that the nuclear segmentation becomes greater with increasing 

 age. Hence cells of Class I with unsegmented nuclei are the 

 youngest. As they increase in age or with progressive seg- 

 mentation Class I gives place to Class II, and this again to 

 Class III, and so on, so that cells of Class V present the oldest 

 individuals where nuclear segmentation reaches its maximum. 



It would therefore appear that by taking phagocytic power 

 as an indication of functional activity, and this again as an 

 indication of the age of the cell, the neutrophile leucocytes 

 with undivided nuclei are young and immature, those with 

 bipartite nuclei being endowed with full functional activity 

 and power have reached adult life, and that thereafter pro- 

 gressively increasing nuclear division indicates increasing age 

 and diminished functional activities. 



These results, whilst they may be taken as in some measure 

 supporting the views put forth by Arneth on the relationship 

 between the age and functional power of the neutrophile leuco- 

 cyte and their behaviour in the various toxaemic conditions 

 present in disease, have also made a considerable addition to 

 our knowledge of the functions and life-history of these cells. 



It has long been known that an increase in the total number 

 of leucoc5^tes in the blood occurs in the condition known as 

 leucocytosis, and that most commonly this leucocytosis is due 

 to an increase in the number of polymorphonuclears present, 

 the number of the other varieties remaining unchanged. 

 An increase in the relative percentage of polymorphonuclears 

 thus results. This total increase in the number of leucocytes, 

 together with an increased relative percentage of polymorpho- 

 nuclears, is met with in ever}'" sort of acute inflammatory process. 

 Thus in acute septic infections, in pneumonia, in erysipelas, in 

 endocarditis, etc., the leucocyte count may rise to 60,000 per 

 c.mm., or even more, the polymorphonuclears giving a relative 

 percentage of 90 to 95. 



Certain chemical substances like nucleic acid and yeast also 

 produce a polymorphonuclear leucocytosis, and this fact has 

 been made use of therapeutically where an incre:."ise in the 

 number of these cells seemed desirable. An increase in the 



