1 8 98 DISEASES OF THE CIRCULATORY SYSTEM 



The polymorphonuclear neutrophile leucocyte is generally 

 called by the first portion of its name. It varies considerably in 

 size, and is characterized by alobulated nucleus in which the lobules 

 vary in number, but however separate they may appear, are always 

 connected by fine threads. It is upon this lobulation that the Arneth 

 count is based, and the form of the nucleus can be explained in the 

 same way as in the transitional (vide supra). 



The basophile leucocyte or mast cell has a trilobed nucleus poor 

 in chromatin and a cytoplasm containing basophile granules. The 

 corresponding myelocytes may under abnormal circumstances 

 be found in the circulating blood, and even at times the pro-myelo- 

 cy tes, which resemble myelocytes, but possess a basophile cyt oplasm 

 with a few neutrophile granules. More rarely cells with a large 

 rounded nucleus containing a fine chromatinic network and three 

 to four nucleoli, and surrounded by an intensely basophile cytoplasm, 

 may be seen. These are Naegeli's myeloblasts. 



Under pathological conditions such as anaemia, with jaundice 

 and leucocythemia, a few plasma cells may be seen in the blood. 

 They are triangular, with an excentric nucleus and a markedly 

 basophile granular cytoplasm. 



The number of white cells varies from time to time from about 

 5,000 to 9,000 per cubic millimetre, but the average is about 7,000, 

 or one to every 700 erythrocytes. 



Following Gulland and Goodall, the average differential count is 

 as follows: — 



The Arneth count formulated in 1904 is based upon the number 

 of lobules in the nucleus of 100 polymorphonuclear or 100 eosinophile 

 leucocytes. Class I. contains those with a single rounded or in- 

 dented nucleus, and would include any neutrophile myelocyte which 

 happened to be present. Class II. has two, ClassIII. three. Class IV. 

 four, and Class V. five lobules. The numbers in Classes I. and II. 

 added together give the Arneth index, and in Classes I., II., and 

 half III. give the Bushnell-Trenholtz index. Arneth subdivided 

 each class into smaller groups by the indentations and the character 

 of the loops and lobes, but these are not now considered. He 

 restricted his counts to polymorphonuclears, but to-day eosinophile 

 leucocytes are also considered. In counting it is wise to follow 

 Chamberlain and Vedder, and to consider as one, lobules with a 

 distinct isthmus, and in cases of doubt to place the number in the 

 higher class. Arneth considered that the youngest cells were those 

 in Classes I. and IT, and that those in Class V. were the oldest, while 

 Classes III. and IV. are believed to be adult. These views have been 

 contested, as has Pottenger's opinion that the phegocytic power 



Per Cent. 



Polymorphonuclear neutrophile leucocytes 



Small lymphocytes . . 

 Large lymphocytes . . 

 Eosinophile leucocytes 

 Basophile leucocytes 



