195 
of Edinburgh, Session 1869 - 70 . 
M. Poiseuille made a single determination of the rate of flow of 
blood serum ; of blood serum plus a small and unknown quantity of 
corpuscles, and of defibrinated blood, the same animal’s blood (an 
ox’s) having been used to furnish the three liquids. The following 
are the results — 
Temperature and pressure stated to have been kept constant 
during all the experiments; length of tube, 110 millimetres; dia- 
meter, 0 mm, 256 ; capacity of receiver, between 5 and 6 C. 0. 
Time of Flow. 
m. s. 
Serum, ..... 20*33 
Serum and a small and unknown quantity of 
blood corpuscles, . . . 21T7 
Defibrinated blood, .... 68*47 
Poiseuille points out that the aggregation of blood-corpuscles, 
which always takes place in defibrinated blood, leads to a choking 
of the tubes employed, especially when these are of narrow diameter 
(0 mm, l), or to an irregular flow, and that consequently defibrinated 
blood cannot readily be injected through the capillaries of the 
lungs of animals which have been bled to death. The recent ex- 
periments of Dr J. J. Muller,* carried on under the direction, and 
according to the method, of Professor Ludwig, in the Physiological 
Institute of Leipzig, are opposed to the statement of Poiseuille, 
for he succeeded in keeping up for long periods a flow of defibrin- 
ated blood through the lungs. 
Method employed in the present research. 
All experiments were conducted according to a method suggested 
by, and under the direction of, Professor Tait, in the Physical 
Laboratory of the University of Edinburgh. The liquids to be 
experimented upon were allowed to flow through tubes of known 
diameter and length, into a large air-pump receiver exhausted to a 
partial and known extent, the fluid being thus subjected to the 
pressure of the atmosphere, minus that of the air in the receiver. 
Before enumerating our experiments, it may be well to point 
out certain fundamental differences which exist between them and 
* “ Ueber die Athmung in der Lnnge von Dr J. J. Muller.” Arbeiten aus 
der Physiolog. Aust. zu Leipzig Mitgetheilt durcli C. Ludwig. Leipzig, 
1870, p. 37-76. 
