STUDIES ON THE PANCREAS OF THE GUINEA PIG 



321 



TABLE 2— Continued 



Distribution of islets of Langerhans in the pancreas of the guinea pig expressed as 

 the number of islets per milligram of pancreas 



*Secretin experiments. 



Table 3 indicates the range of variation in islet content exhibited 

 by neighboring pieces of the pancreas. The determinations were 

 made in order to test the validity of the assumption which is made 

 in experimental work on the islets of Langerhans that a sample 

 taken from the corresponding portions of several pancreases rep- 

 resents the proportional islet content of those pancreases. In 

 order to do this a small portion of the splenic end of a pancreas 

 which was injected with neutra^l red was divided into suitable 

 portions, and the total islet content and weight of each portion 

 was determined. The result shows that the islet content of adja- 

 cent parts of the same pancreas may vary within wide limits and 

 accordingly that islet estimates made on this basis are not a trust- 

 worthy indication of the real islet content of the pancreas. 



THE EFFECT OF CERTAIN EXPERIMENTAL METHODS ON THE 

 NUMBERS OF THE ISLETS OF LANGERHANS IN THE PANCREAS 



Table 1, showing the great variation in total number of islets 

 for different ages and weights and for the same weights, table 2, 

 showing the variations in the distribution of islets in different parts 

 of the pancreas, and table 3, showing the inequalities in numbers 

 for equal weights of pancreas from the same portion, taken to- 

 gether, illustrate very well the pitfalls that await the experimen- 

 tal investigator who seeks to determine what effect a certain 

 procedure has upon the number of islets in the pancreas. To 

 determine the direction of the change if any, and to estimate its 



