10 CONTROL SERIES No. 63 



2. Dilute antigen of a pH 8.4 did not suffer an appreciable decrease in any 

 of its essential qualities in a period of 15 weeks when held at a temperature 

 approximately 8° C. 



3. Addition of sufficient sodium hydroxide to adjust the pH to 8.3-8.5 did 

 not cause a detectable autolysis or clearing in dilute antigen during 15 weeks of 

 storage at approximately 8° C. 



4. Slight variations in the morphology of stock cultures held at 8° C. or 

 transferred to fresh medium weekly were observed. 



5. Antigens from cultures transferred weekly or stored at a temperature 

 of approximately 8° C. for 49 weeks were as satisfactory for use in making agglu- 

 tinable antigen as cultures held at 22° C. and transferred at monthly intervals. 



JELLIED BLOOD SAMPLES 



In this laboratory jellied chicken blood samples are an important problem 

 in preparing agglutination tests for the detection of pullorum disease carriers. 

 An investigation was undertaken because most of the jellied blood samples re- 

 quire extra handling and some of the tests are not very satisfactory. There seems 

 to be a scarcity of discussion on jellied samples in the literature on pullorum 

 disease. At the first conference of Laboratory Workers in Pullorum Disease 

 Control in 1928, and at later conferences, other laboratories reported occasional 

 experiences with such samples. 



In Massachusetts, the routine pullorum disease testing season extends ap- 

 proximately from September first to March first. The blood samples are collected 

 by trained personnel designated as blood collectors. From an incision in the 

 wing vein, 0.5 to 1 cc. of blood is collected into an 8 x 77 mm. tube. While the 

 tubes are placed in a slightly inclined position, the surface of the coagulum does 

 not become slanted. At the end of the day's work, the samples are iced, shipped 

 by express, and usually arrive at the laboratory the following morning. After 

 separating the clots from the walls of the tubes, the samples are centrifuged, 

 and sera are transferred to agglutination tubes. 



The term "jellied" as used in this report refers to a blood sample in which 

 the supernatant serum presents the consistency of jelly. Such samples in the 

 process of jellying may show various characteristics. Among the samples re- 

 ceived at the laboratory some were not clotted 18 to 48 hours after collection. 

 Appro.ximately 50 per cent of these samples may jelly. The supernatant serum 

 in some samples may be jellied while the blood constituents below will be in a 

 fluid state. Furthermore, the entire column of serum is not always jellied. The 

 lower portion of the column may be in a fluid or semi-fluid state, either with or 

 without inclusion of blood cells. Occasionally the serum column may be com- 

 pletely jellied, containing either scattered cells or no cells, with the blood column 

 below formed into a firm mass. A clotted sample, apparently normal, may yield 

 jellied serum after dissociation of the clot and centrifugalization. In the majority 

 of jellied samples liquid serum is obtained when the blood mass is dissociated 

 and centrifuged. It may be necessary to repeat this procedure several times to 

 obtain liquid serum. Infrequently, the serum in the agglutination tube and rarely 

 the antigen-serum mixture become jellied. 



Preliminary Observations 



This investigation was started in September, 1930. Earlier general observa- 

 tions concerned blood samples which were placed in an incubator at approxi- 

 mately 37° C. for 45 to 60 minutes. This exposure of the blood samples to heat 

 either before or after centrifugalization appeared to influence the number of 

 jellied samples. 



