336 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1952 



The quartz-rod transilluminator. — One of the most fascinating 

 techniques that has been devised in the last few years is that of the 

 quartz-rod-transilluminator method of Dr. Melvin H. Knisely, head 

 of the Department of Anatomy, University of South Carolina. This 

 technique permits light to be brought to living tissues in which heat is 

 not transmitted. Only the heat of irradiation is present, and this can 

 be eliminated or drawn off by the continuous flow of normal physio- 

 logical salt solution over the tissue being observed. Three outstanding 

 discoveries in recent years have been made by the use of this tech- 

 nique. In 1935, Knisely discovered that the spleen had a closed circu- 

 lation and had the power of regulating the amount of formed elements 

 of the blood held within one of the individual units of the spleen, 

 namely, the sinusoid. This observation was a rather striking dis- 

 covery. Knisely could actually see the sphincter activity of an indi- 

 vidual sinusoid after it began to constrict and hold back the blood cells 

 while at the same time allowing the plasma to escape through the lat- 

 ticelike wall of the individual sinusoid. In studying the liver Knisely 

 also showed that there was a sphincterlike activity at the point just 

 before the sinusoid enters the central vein. In both the spleen and 

 liver he showed that there was a rhythmiclike activity of filling and 

 emptying the individual sinusoid. He also established the rate of red 

 cell destruction by the liver in its selective phagocytic function. Here 

 he showed that as a red cell became old or injured in some way, a lin- 

 ing cell of the liver sinusoid instantaneously engulfed the red cell. 

 This effect was not only observed and reported by Knisely, but his 

 color photography is superb in showing the above activity. Knisely's 

 discovery of sludged blood was a unique revelation to the medical pro- 

 fession. Using the quartz-rod-transilluminator method, he showed 

 that under pathological and disturbed conditions in all animals studied, 

 red cells of the blood stream were agglutinated within the vessels them- 

 selves. Even in minor injuries, especially in surgical shock, sludging 

 became excessive. In more than 600 human patients observed by the 

 quartz-rod-transilluminator method in the sclera of the eye, Knisely 

 has observed a sludging of blood. This sludging is observed in vary- 

 ing degrees of intensity from the result of a minor cold in which there 

 is very little sludging to extreme cases of malaria where excessive 

 amounts of sludging occurs. Knisely has concluded from his studies 

 that all human ills produce this phenomenon. 



The next big step that will follow undoubtedly will be a discovery 

 of some method of "unsludging" the blood. Intensive studies in 

 several laboratories are now under way to understand more clearly 

 the factors involved in producing the sludge in the first place. The 

 study of sludging is being observed on experimental animals with 



