58 
In reading the proper height of the fluid in these flasks the bottom 
of the meniscus is brought just to the line. By holding a black sur- 
face, such as a piece of cloth, beneath the level of the fluid the reflec- 
tion makes the surface of the fluid stand out clear!}" as a single curved 
line, doing away with the annoying reflections that otherwise prevent 
accurate readings. This black curve of the meniscus is best seen 
against a white background. 
The use of the ‘‘meniscus visir blende” of Doctor Gbckel greatly 
facilitates the accurate reading of burettes, pipettes, and flasks. This 
little apparatus is exceedingly simple. It ma}" be improvised in any 
laboratory, and will be found very useful. 
All the glassware used in this work is cleaned by first flushing with 
cold, then with hot water, in order to remove the gross dirt. It is 
then bathed in a saturated solution of bichromate of potassium in 
concentrated sulphuric acid. The glassware is now flushed with tap 
water until all the acid is removed, when it is finally rinsed in several 
changes of distilled water and allowed to dry in the air. 
All glassware is sterilized by heat at 125° C. for one hour, and kept 
under the usual precautions to prevent i)acterial contaminations. 
AH' the glassware used in this work has been standardized to contain 
or to deliver fluids at 20° C. instead of 15° C., because the former 
more nearly approaches the usual room temperature in this climate. 
The serums and toxines are removed from the ice chest a suflicient 
time before using to allow them to stand (in the dark) until thej 
approach the room temperature before they are measured out. 
The dilut eng fluid . — We use “physiological” salt solution (0.85 per 
cent, sodium chlorid C. P.) as our diluting fluid for all toxines, serums, 
etc. This salt solution is made up in bulk with distilled water and 
sterilized l>y steam. It is always used at room temperature. 
Bacterl()le>giccd precceutions . — All the work is done under the usual 
bacteriological precautions to prevent contamination. We do not 
observe the extreme precautions necessary to obtain a pure culture of 
an organism. The toxine and antitoxin are of course kept under per- 
fectly sterile conditions and all the glassware with Avhich they come into 
contact is clean and sterile, which appears sufticient to prevent con- 
taminations entering the work that would affect the results. The 
autopsies made in this laboratory have so far failed to reveal any such 
infections of the guinea pig. Cultures were made from 151 consecu- 
tive guinea pigs. Some of* the heart’s blood was inoculated into bou- 
illon tubes. Of these tubes 108 i*emained sterile; growth appeared in 
d6, as follows: 
A coccus in 20 
Motile bacillus in 18 
Nonmotile bacillus in 5 
Coccus and bacillus in 3 
46 
