10 



FALLACIES AND I'TZZLKS IN" HL0O1) EXAMINATION 



\ilventi(ious 



l.iUacics 



N'casl cells, 

 pollen grains, 

 and debris 



l\>ssibilily of 

 inteslinal 

 parasites In 

 lilood films 



For convenitMicc one may divide tliose conditions into two classes according to 

 their origin : — 



1. External, Adventitious or Heterogeuetic. 



2. Internal or Autogenetic. 



In the first class we consider cases in which the souree of fallacy oi- the j)ii/,/liiig 

 condition is derived from outside the blood itself as, to take a classical example, the 

 inclusion of insect hairs in a film simulating filariie. This is the view taken by Low and 

 Stiles of the Filaria ijiijas described by Piout. It is perhaps scarcely necessary to mention 

 another case in which cotton fibres, gaining access to blood films, led to a wholesale 

 diagnosis of filaria cases. This is the type of fallacy which care and cleanliness, the 

 watchwords of a hiematologist, should avert. 



For several reasons Class I. is moie likely to be found in stained blood and it is 

 sometimes far from easy to come to a definite conclusion, especially when one is examining 

 films prepared by another person and perhaps sent from a distance. It may then be 

 impossible to make that examination of the fresh blood film which so often clears up a 

 difficulty. In this connection one would cite the frequent presence of yeast cells in 

 films made in the Tropics. Of this nature are the curious bodies described by Neave, 

 illustrated in the Second Report of these Laboratories and here again reproduced 

 (Plate VI., figs. 1 and 2). The occurrence of chromatin-like granules in such cells is apt 

 to be confusing as is the definite arrangement of a capsule or enclosing membrane and the 

 frequent presence of definite segments. Such bodies are not likely to find their way 

 into fresh blood preparations which have perforce to be quickly made, but they are very 

 likely to be blown by the wind on to films whicli, though drying, are still wet, and in such 

 a case they may, to all appearance, be on the same level as the corpuscles. 



Possibly also yeast spores may develop to some extent in blood films and produce 

 confusing pictures. 



In the same category come pollen grains and animal and vegetable debris found in 

 dust, but in my experience these are not so common nor so puzzling as the yeast cells. 

 These latter may gain access to blood films in another way, and in this connection I quote 

 a paper which I had occasion to write in connection witii the finding by Professor Nuttall, 

 of Cami)ridge, of a new spirocluete in the African buffalo. I'rofessor Nuttall's original 

 paper, which drew forth my comments, should be consulted, and his drawings — republished 

 here by his kind permission — -may with advantage be compared with those I here submit 

 and which represent the similar bodies in tin: films from the hartebeeste.' (IVi/c 

 Figs. 2K and 29.) 



I also present Professor Nuttall's interesting rej)ly and, while tiie (juestion still 

 remains open, would insist on the recognition of this source of error. 



" I have been much interested in Professor Nuttall's paper in the April munber of 

 Pariisitiiltiiiy (Vol. III., p. 113) and especially in his description of a parasite found 

 by liim in blood smears from a buffalo sent to Englan<l from Jlritish Ivist Africa. He has 

 named this organism Spirochn'ta borin cuffn'y though he is evidently somewhat doubtful as to 

 its nature. I write to say that early in 1909 I received from Captain Iladow one blood 

 smear from a Jackson hartebeeste which he had shot in the Bahr-El-Ghazal and on 

 the body of which he found '/. iiKin-ilmis in the act of feeding. In this smear I found 

 organisms which answered very closely to those described and figured by Professor Nuttall 



' Tlirouijli the kindness of Professor f). II. F. Nuttnll, F.H.S., it 1ms Keen pos.sil)le to roproduee his 

 illustration (Fij;. 20) of the Spiroclmln bm-is ai[fris described by him in /'iii-a.iili>liyii. Vol. Ill, No. 1, 

 April 30, 1910, /</<. 113 and 114. 



