Laking of Blood by Drying. 



151 



degree to which the temperature was lowered, and to the length 

 of time during which the low temperature was maintained. 



93 (9io) 

 Laking of blood by drying. 



By C. C. Guthrie and M. E. Lee (by invitation). 

 [From the Physiological Laboratory, University of Pittsburgh.] 



Drying of blood may cause laking of the scarlet blood discs. 1 

 To obtain more information regarding the phenomenon, the ex- 

 peiments reported in this communication were undertaken. 



The phenomenon may be produced in a number of ways. 

 Perhaps the simplest is to prepare an ordinary wet blood mount 

 and to observe it with a microscope. Another method is to make 

 an ordinary blood smear and allow it to dry quickly in the air and 

 then place it film side down on a microscope slide and after 

 focusing it under a microscope, place a drop of serum, salt solution 

 or other liquid on the slide, so that the edge of the drop forms 

 contact with the edge of the slip and will spread under it. 



Under these conditions laking occurs and may be readily 

 observed in the individual discs. 



In the case of a wet mount, the process is slow and various 

 stages may be seen. If drying be rapid the individual discs may 

 lose their hemoglobin with slight or no change in size. But if it 

 be more gradual, they may be seen to swell before laking. This is 

 also the case with shrunken or crenated discs. 



In the case of dry mounts, the hemoglobin is almost instan- 

 taneously dissolved on contact with the liquid under the slip. 

 If any change in the size of the discs occurs, it has not been 

 observed. 



At present the manner in which laking is thus produced is not 

 known. Drying is, of course, accompanied by concentration of 

 salts or other substances present in solution or suspension both 

 within the discs and in the serum. Now it is known that hyper- 

 tonic solutions of such substances if caused to act on the blood 

 may produce laking. Therefore, the question arises, Is laking 



1 Am. Jr. Phy., 1903, VIII, 441. 



