whether the structure itself is perfectly sound. He then builds further, but in most cases makes only a tiny addition. It is very easy for a single observer to lose a clear view of the whole, through using too complicated a scaffolding. Others follow; they test the solidity of the structure, they move the misplaced bricks into their correct position, and give a finishing touch to the parts that are insufficiently trimmed. Each new workman brings new tools, new ideas, and his own extensive experience with him, and tackles the whole structure from different points of view. Then the scaffolding is removed, and a mighty building appears, which scarcely gives any idea how diverse were the plans on which it was founded. So, too, this contribution to our knowledge of the functions of the cells may be considered only as an attempt to adjust a new stone in the already existing structure, and to construct a scaffold from which further progress may be made.
In conclusion, may I be permitted to express my heartiest thanks to my collaborators, whose untiring energy has made it possible to accomplish so many single experiments in such a relatively short time, and to work out different problems from various standpoints at the same time.
Halle a/S.,
April 15, 1912.
