When comparing the modern Souverän M400 and its historical ancestor from 1929, you will find a number of similarities. You will find a cap in which a clip is inserted between the cap head - or in today's models, the cap crown - and the cap sleeve and held in place by these two parts. The cap itself is screwed onto a thread on the fountain pen, just above the grip section.
Then, as now, a nib assembly, consisting of nib, ink conductor and bushing, is screwed into the barrel. The piston mechanism, of which we see the filling grip at the end of the barrel, also functions essentially as it did back then.
In detail, the changes to the basic Model 100 are so varied over the 14 years of its production that we can only attempt to give an overview here. Special features like decorated clips for the Toledo, differently designed "Danzig" variants and analog special shapes are not completely considered or only mentioned textually.
The consideration is thus reduced to the standard model and its modifications, which were made on the basis of experience, technical progress and external influencing factors.
The multitude of changes, which are presented chronologically as far as possible, nevertheless does not allow an exact chronological determination of individual fountain pens. On the one hand, it is not always known from which point in time a change was made, and on the other hand, stocks were used as they were available, so that, especially in the borderline periods, a mixture of materials, for example, when production was switched to injection molding, is quite typical and cannot be attributed exclusively to later repairs.
By the way, the concrete dates of certain changes come from catalogs or notices of the company Günther Wagner in the information publication "Pelikan Blätter".