311 
1916-17.] Observations on the Blood in Gas Poisoning. 
looking, but on examination nothing was found but a few rhonchi in the 
lungs. The case being a puzzling one, a blood examination was resorted to, 
and on making a differential count 39 per cent, of polymorphs and 51 per 
cent, of lymphocytes were found. The total number of leucocytes was 6562 
per c.m. The conjunction of a lymphocytosis with gassing was regarded 
as significant, and on further investigation the sign was found to be 
characteristic of such cases. We published a short note in the Lancet , 
January 6, 1917, describing 14 cases with blood counts. Our observa- 
tions have now been extended to 50 cases, the main points in which will 
be found in Table I. 
In our original communication we made the statement that the change 
takes some time to develop, probably three to four months. Further 
observation has shown that this is not necessarily so, for in Cases 33 and 
39, which were observed respectively one month and six weeks after 
gassing, the change was already well marked. 
Recently we had the opportunity of examining the blood of an officer 
who was accidentally gassed in this country with chlorine. The accident 
•happened on January 24, 1917, and the blood was examined on 
January 27, 1917. The red cells numbered 5,500,000, the haemoglobin 
was 98 per cent., and the white cells were 5900 per c.m. Beyond a slight 
leucopenia, there was therefore no change. The differential count was 
normal, polymorphs 68'5 per cent., and lymphocytes 25*5 per cent. 
Little can be gathered from the evidence of a single case, but what 
evidence there is goes to show that the gassing results in a destruction of 
leucocytes, but that at such an early stage there is no stimulation of any 
one type of leucocyte. The case was a very slight one, the patient return- 
ing to duty within a week of the gassing. 
In order to ascertain whether the relative lymphocytosis is due to an 
actual increase in the number of lymphocytes or to a diminution in the 
polymorpho-nuclear leucocytes, we have constructed Table II, giving a 
series of cases taken at random in which a leucocyte count was made in 
addition to the differential count. From the two data — number of leucocytes 
per cubic centimetre, and percentage of the two main types found — the 
actual number of lymphocytes and polymorpho-nuclear leucocytes has been 
given in figures. The first lines of the table give the average in normal 
cases at what may be taken as the physiological limits and the mean 
(Gulland and Goodall, The Blood , 2nd edition, p. 78). This table shows 
that in all cases the sign is marked (the only exceptions in the table 
being Nos. 10, 11, and 16, which were comparatively slight), and there is 
an absolute increase in the number of lymphocytes. In certain cases 
