92 



Previous Estimates. 



Opie (1900) appears to have been the first to study the rela- 

 tive distribution of the islands of Langerhans in the human pan- 

 creas. The following figures represent in his series the mean number 

 of islands ' ' found in 0.5 square centimeters of section about 10 microns 

 thick, taken from the head, body and tail of the normal organs": 

 head 18.3, body 18.0, tail 34.0. Comparing these with the results 

 of other observers, we find they are much lower. Thus "averages 

 (17 individuals) calculated from the number of islands of Langerhans 

 found by Heiberg in 0,5 square centimeters of tissue are as follows: 

 head 69.5; body 94.3; tail 143.8. These figures differ but httle from 

 those of Laguesse and Sauerbeck," (Opie). Laguesse's estimate 

 gives 1 islet per sq. mm. and Sauerbeck's 1.52 per sq. mm. in sec- 

 tions 10 [JL thick. 



Opie observes ' ' they are almost twice as numerous in sections 

 from the tail as in those from other parts; but since the number in 

 only one plane is recorded, in order to obtain their actual relative 

 abundance, it is necessary to square these figures." It is obvious, 

 however, that this method would lead to erroneous results, the error 

 increasing proportionally to the increase in area used for the com- 

 putation. It is apparent that in order to obtain correct results we 

 must reduce one of the factors of this computation to unity and mul- 

 tiply the other by its square root to obtain in the one case the number 

 of islands for unit volume of pancreas, in the other the volume of 

 pancreas for unit number of islands. Applying this method to the 

 counts of Opie, Heiberg, Laguesse, Sauerbeck, Dewitt, and the 

 writer, the following values for the number of islands in a cubic 

 centimeter of pancreas from the three principal regions would be as 

 follows : 



Opie's figures give 233 islands per c. c. for the head of the pan- 

 creas, 216 for the body, and 557 for the tail; Heiberg's 1626 for the 

 head, 2583 for the body and 3760 for the tail: Laguesse's 1000 per 

 c. c. ; Sauerbeck's 1869 per c. c; and Dewitt, 1300 in the newborn, 

 3142 in a four year old child, and 1896 in an adult. The numbers which 

 I have obtained in three cases, by actual counting of the islands and 

 weighing the pieces of pancreas in which the islands had been counted, 

 are much higher. They are as follows: head, maximum 25,250, 

 minimum 4180, average 12910; body, maximum 16160, minimum 

 2700, average 9856; tail, maximum 11920, minimum 5320, aver- 



