196 GOTTWALT CHRISTIAN HIRSCH 



use the same species of animals or do not follow the same points of time 

 in the cell production processes. And, indeed, the same species of animals 

 show individual differences in time in their answer to the same stimulation ; 

 in other words, individuals of the same species differ in their production 

 curves. 



But in spite of all these difficulties it is possible to get a tentative scheme 

 of the "production line" of every species and every gland cell under the 

 following conditions : 



Secretion is a long sequence of processes in time [64, 65]. I believe it 

 may be necessary to follow this sequence by putting every qualitative and 

 quantitative datum on a single time co-ordinate [64]. Some investigations 

 are ill-timed because they are made with animals, whose timing of secretion 

 is unknown. There are, so far as I know, only two ways of timing [70, 71]. 



First to investigate the ontogeny of gland cells during the development 

 of many well-known stages from the first "Anlage " of the cell to the stage 

 in which the "professional" structure and function of the cell has been 

 constructed [2, 11, 45, 46, 70, 121, 122, 126, 145, 179, 180]. 



The second way may be to investigate the secretion cycle by com- 

 paring the biochemical and structural information [66, 10 1] first during 

 the so-called "starvation time" in which the sequence of secretion pro- 

 cesses is stopped or is very slow — second during the "activation time" 

 after a certain stimulus. This "activation time" is one phase of secretion 

 in which the extrusion of the old secretion product takes place, following 

 the restitution and storage of the new products. This phase continues in the 

 pancreas for about i to 5 hr. [66] ; during the 1st hour the most important 

 processes of restitution take place [71-72]. During this phase it is, there- 

 fore, necessary to investigate not only one point of time, but many points 

 during the 1st hour and some points during the 2nd to 5th hours. 



The number of methods of these investigations are numerous. I may 

 say that the first necessary step is to observe the living cell, either as an 

 isolated cell in tissue culture or preferably as one cell in living relation- 

 ship with other cells inside the tissue. It is possible to observe the living 

 tissue of the pancreas under physiological conditions during 8-10 hr. 

 under the light microscope [66, 67]. Only in this way can an outline of the 

 time of production processes be obtained. 



The second way is the study of the life cycle of a cell [64-72] : you start 

 your investigation with a more or less uniform stage of so-called "resting 

 cells" during the starvation of the animal [7, 68]. Then you give the 

 stimulus of feeding, of drugs, of nervous or of hormonal excitation always 

 at the same time after the beginning of starvation (e.g. 1 or 2 days). Then 

 you investigate the animals at different times after the same stimulus: 

 e.g. 3, 5, 10, 20, 40, 60 min. and 2, 3, 4, 6, 8 hr. after stimulus. For every 

 point of time three animals may be used. Every animal is treated by the 



