144 Immunity 



tests that some transformation has been effected. For the latter 

 Abderhalden has made use of, two separate tests: 



The first of these is rarely employed, the second is now regularly 

 employed. 



I. The Optical Test. — This depends upon the fact that in the 

 transformation of protejn substances, aminoacids may be formed, 

 some of which are optically active. The contact of the enzymic 

 serum and the appropriate sub-stratum is permitted to take place, 

 then after the appropriate length of time, the polariscope is employed 

 to determine whether rotation differences obtain because of the 

 presence of transformation products. 



II. The Dialysis Test.- — This test not requiring apparatus or skill 

 of unusual or special kind, has met with greater favor. Its first 

 employment was for the demonstration of the presence, in the blood, 

 of an enzyme that would transform placental tissue. As no such 

 enzyme appeared in the blood except placental tissue* was in the 

 body, it became a test for the determination of the existence of preg- 

 nancy. The method required but little in the way of special appar- 

 atus or reagents. The chief requirements being small "dialyzing 

 shells" or thimbles, which are made by Schleichter and Schull, and 

 are commercially known as No. 579(1. They are procurable through 

 importing agents dealing in laboratory apparatus. These shells 

 must be tested before using, and it is best to test a large number at 

 the same time. Each must be impervious to albumen, but readily 

 permeable to peptones, aminoacids and other cleavage prodiicts of 

 protein digestion. 



The shells or "thimbles" are tested thus by Kolmer:* 



They are first soaked in sterile distilled water for half an hour or more, until 

 they are softened. Each then receives about 2.5 cc. of a s per cent, solution of 

 egg-albumen in distilled water, thoroughly mixed and freed from flakes or shreds. 

 In filling the shell, care should be exercised that none of the albumen solution by 

 any chance falls upon the outside. The shell is then picked up with forceps and 

 transferred to a short tube containing about 20 cc. of sterile distilled water. 

 This tube should be so wide that the column of water is not so deep as the shell is 

 high, and not so broad that the shell is in danger of oversetting. . As bacteria 

 may not have been successfully excluded and by multiplying may cause proteo- 

 lytic cleavage of the albumen, it is well to cover the fluid in the thimble and tiiat 

 in the tube outside of it, with a thin layer of toluol. The outer tube is' plugged 

 or corked, and the whole is stood in the incubating oven where it is kept at 37°C. 

 for sixteen to eighteen hours. At the end of this time, 10 cc. of the water in the 

 outer tube is removed by a pipette, and tested by the biuret reaction to determine 

 whether any albumen has penetrated the thimble. For this purpose the fluid, 

 in a test-tube, receives 2.5 cc. of a 33 per cent, solution of sodium hydroxid and is 

 shaken gently. One cubic centimeter of a 0.2 per cent, cupric sulphate solution 

 is permitted to trickle down the side of the tube and overlie the contents. If a 

 delicate voliet is produced at the line of junction of the two liquids, albumen has 

 escaped from the thimble intothe water putside. Under such circumstances the 

 thimble is, of course, useless and should be thrown away. If there is any uncer- 

 tainty about the reaction, the tube can be stood away for eight hours or so longer 

 (twenty-four hours in all) and the remaining water subjected to the ninhydrin 

 test (see below). 



* "Infection, Immunity and Specific Therapy." Phila., 1915; p. 253. 



