12 DEPARTMENT BULLETIN 3 19, U. S. DEPT. OE AGRICULTURE 
pears. The dose may be reduced after implantation is established. 
It has been found possible to maintain the implantation, when once 
it is established, by the daily use of 100 to 250 grams of lactose taken 
in the diet. Acidophilus milk is best taken between meals so as not 
to interfere with the appetite, and the daily quantity may be divided 
into several portions. It is frequently made more palatable by add- 
ing orange or lemon juice. 
Lactobacillus acidophilus was first isolated by Moro in 1900 from 
the feces of infants, and he describes it as a gram-positive rod. 1.5 
to 2 fx long and 0.6 to 0.9 p wide. Surface colonies on agar plate? 
have a hairlike periphery, but few threads are seen on deep colonies. 
Growth is scant on agar slopes. L. acidophilus produces acid and is 
tolerant to high acidity. It produces no gas. Albus and Holm (1) 
have shown that L. acidophilus grows very well in a medium the 
surface tension of which has been depressed with sodium ricinoleate 
to 36 dynes, whereas L. buIgaHcus is unable to grow in the same 
medium depressed below 40 dynes. This is offered as a means of 
culturally differentiating between these two closely related organisms. 
The commercial production of acidophilus milk is practical, and 
the product is now being manufactured in large quantities in some 
localities. 
The manufacture of pure acidophilus milk requires the greatest 
care, both in the preparation of the milk before inoculation and 
throughout the entire process of manufacture. It must be remem- 
bered that L. acidophilus is not a natural inhabitant of milk and 
must be acclimated to this medium. Even though it be acclimated 
to milk, its growth is nevertheless such that it is unable to overcome 
a slight contamination. Laboratory facilities, close supervision, and 
adequate equipment are essential to the successful production of 
acidophilus milk. 
The first step in the manufacture of acidophilus milk is to obtain 
from a reliable source a pure culture of the bacterium Lactobacillus 
acidophilus of proved therapeutic value. After a pure culture is 
obtained it must be kept pure as a starter. All chances of contamina- 
tion must be avoided. Florence or Erlenmeyer flasks are the most 
suitable containers in which to carry the starter. The flasks should 
be about half filled with fresh skim milk and plugged with cotton. 
They are then sterilized in an autoclave at 15 pounds pressure for 
20 minutes. The milk after sterilization has a slightly caramelized 
appearance. After the milk has cooled, a flame from a gas burner 
should be passed over and around the mouth of the flask and the 
culture introduced into the flask after the mouth of the culture tube 
is passed through the flame. The cotton plug from the flask should 
be held in the hand during this operation and replaced in the mouth 
of the flask immediately after inoculation. The inoculated milk is 
incubated at 98° to 100° F. until the milk has curdled. A starter 
should show a small quantity of whey on top of the curd which should 
appear firm with no evidence of gas. The curd is broken up by 
rotating the flask vigorously. The starter should be of a creamy 
consistency and possess a clean acid flavor and a characteristic aroma. 
This starter, or mother starter, is carried on by daily transfers from 
flask to flask. The same procedure as described above is followed 
except that usually the first bit poured over the lip of the flask is 
