THE EXTERNAL SECRETION OF THE PANCREAS AS A WHOLE 1 97 



same technique, biochemical or structural. These techniques are numerous : 

 vou can perhaps observe the living cell [66], or study the secretion product 

 by fistula [68, lOO, loi], or kill many animals in the above-mentioned times 

 after stimulus and compare the different stages of the cell cycle [185]. The 

 main point seems to be that all the different techniques are applied at the 

 same points of time. In this manner you will really be able to integrate the 

 results of different techniques. Only the integration of all the different 

 data gives a sequence of processes and only a sequence of events gives an 

 idea of the life of a secretion cycle [70, 71] showing us the "assembly 

 line" during restitution of the product. 



2. The life cycle of the exocrine pancreas cell 



The life cycle may be divided into three phases : the ingestion of raw 

 material, the synthesis, and the extrusion of products [69 72, 140]. 



The ingestion [66, 10 1] consists of active transport of material from 

 the blood through the basal membrane (surrounding a whole acinus) and a 

 cell membrane [159-161, 182]. The influx of this material in some cases 

 seems to be changeable and higher after stimulation than during starvation 

 of the animal. Proteins of the blood plasma are not ingested, only amino 

 acids [100]. 



The synthesis of enzymes may be shown by the schematic Fig. i and 

 may be divided into the following steps : 



I. The ingested amino acids [15, 27, 56, 62, 88-90, 100, 104, 105, 124, 

 156, 162, 191] and phosphates [19, 20, 57, 101-108, iii, 125, 154, 165, 

 201] in the fluid basic substance and the polynucleotides from the cell 

 nucleus [30, 47, 62, 1 14-1 16, 128, 170, 181] arri\e at the ribosomes (ribonu- 

 cleoprotein granules) [5, 12, 26, 58 61, 117, 120, 141 143, 188, 194-197, 

 200, 203, 206] and are absorbed [18, 173 177]. From the cell nucleolus 

 ribonucleic acid reaches these granules [48 55, 73, 74, 77-80, 93, 109-113, 

 148]. Phosphates of high energy may be formed by mitochondria as an 

 energy source [76, 166]. With the aid of these substances proteins are 

 synthesized in or on the ribosomes [76, 144]. 



During starvation of the animal and i hr. after feeding, the ribosomes 

 have the same size of --150 A diameter and the same optical density. 

 Their number is considerably greater, however, during the restitution 

 period : according to the electron-microscopic pictures of Palade I would 

 say about ten times greater. One may deduct from this that the ribosomes 

 multiplv during the ist hour after feeding. This multiplication has also 

 been observed during ontogenesis [2, 46]. How these granules multiply, 

 however, is still not clear [13, 43, 44, 178]. Forms of division have not 

 been seen. I have now come to the following hypothesis which I put up 

 for discussion: the fluid cell plasm contains free, dissolved ribonucleic 



