Accmthurus triostegus sandvicensis — Randall 
229 
wrote that the carp has more than 1,000 times 
the amount of amylase in the pancreas than that 
of the carnivorous pike or shark. Schlottke 
( 1939) found amylase in large quantities in the 
carp, whereas the predaceous rainbow trout 
(Trutta iridea ) and perch ( Perea fluviatilis) 
evidently produced almost no amylase. Data 
comparing the activity of proteinase and lipase 
of omnivorous and carnivorous fishes are meager 
and conflicting. 
In view of the importance of the hydrogen 
ion concentration to enzyme activity, the pH of 
the contents of various parts of the digestive 
system of the manini was determined. The meas- 
urements of pH were made with a Beckman pH 
meter on six adult fish which averaged 120 mm. 
in standard length. The results, expressed in the 
ranges of pH found, are given in Table 4. 
The variation of pH within any one organ 
appears to be correlated with the degree of full- 
ness of the organ. The low pH values were 
found in the organs when they were filled with 
algae. Hydrochloric acid secretion in a stomach 
in which food is present is a probable explana- 
tion for the greater acidity at this time. Babkin 
and Bowie (1928) found a variation in pH of 
the duodenum of the killifish ( Fundulus heter- 
oclitus) similar to that shown above for the 
manini. These authors also noted that low values 
of pH were obtained when the duodenum con- 
tained food. They attributed this to the discharge 
of bile to the organ when filled with food. 
Extracts for the enzyme study were consist- 
ently prepared from the stomach (both cardiac 
and pyloric portions combined), pancreas, py- 
loric caeca, duodenum, and intestine of adult 
manini which were killed immediately before 
the removal of these organs. Because of the ex- 
cessive thinness of the gut wall, it was very dif- 
ficult to separate the mucosa from the muscle 
layers; therefore extracts were made of entire 
organs or linear parts of organs. All portions 
of the digestive tube to be extracted were first 
washed with sea water to remove food material. 
Tissues were ground in mortar and pestle with 
calcareous sand. This sand had previously been 
cleaned by repeated washings with water, boiling 
with 3 per cent potassium hydroxide and then 
for a short while with 2 per cent hydrochloric 
acid. In view of MacKay’s (1929) report that 
TABLE 4 
pH of Organs of the Digestive System of 
Acant hunts triostegus sandvicensis 
ORGAN 
RANGE OF pH 
Stomach 
6. 3-7.7 
Duodenum 
7. 7-9.1 
Intestine 
8.0-9. 1 
Gall bladder 
6.2-64 
30 per cent alcohol yielded the most active amy- 
lase from the eel pout ( Zoarces anguillaris ) , 
this agent was also used to extract amylase in 
the present study. Lipase extracts were made in 
40 per cent glycerol and protease extracts in 50 
per cent glycerol. Extraction was carried out in 
a refrigerator for a period of 24 hr. 
Digestion by amylase and lipase proved to be 
rapid at room temperature (26°-27° C); thus 
no incubation was necessary in experiments with 
these enzymes. Digest tubes with protease were 
incubated at 36° C. 
Buffer solutions used in the digestion experi- 
ments were based on the mixtures of Clark and 
Lubs (Hawk and Bergeim, 1942: 24). Bacterial 
action was prevented by the addition of several 
drops of toluol to the extract and digest test 
tubes. 
The substrate for amylase experiments was 1 
per cent starch solution. To each test tube con- 
taining 1 ml. of extract of the digestive organs 
5 ml. of starch solution and 1 ml. of buffer of 
pH 6.8 were added. For each tissue there was a 
control tube identical with the experimental di- 
gest tube except, for the previous boiling of the 
extract to inactivate all enzymes. 
The progress of digestion was followed by re- 
moving small amounts of fluid from the digest 
tubes and testing with Lugol’s solution. The 
changes in the solution from deep blue-black 
through purple, red, yellow, and finally colorless 
indicated a breakdown of the starch at least to 
achroodextrine. Ultimately all of the tubes were 
colorless, thus disclosing starch digestion by the 
pancreas, pyloric caeca, duodenum, intestine, and 
stomach. The experiment was repeated three 
times with sections of the digestive tract vig- 
orously washed to minimize the possibility of 
enzyme from another source being adsorbed on 
the epithelial surface of the organ being tested. 
