_Kossel’s Analysis. Hexonic Nucleus._—Kossel has approached the problem in another fashion. He did not attempt to attack the albumin of the egg. This body is, in fact, a heterogeneous mixture as complex as the needs of the embryo of which it forms the food. Kossel tried a physiologically simpler albuminoid. He got it from an anatomical element having no nutritive rôle, of a very elementary organization and physiological functional activity, and yet one of energetic vitality—the male generating cell. Instead of the hen’s egg he therefore analyzed the milt of fish, and, in the first place, of salmon. As was to be expected from what has been said of the proteids, this living matter gives a combination of the nuclein, already known, with an albumin. The latter is abundant, forming a quarter of the total mass. Its reaction is strongly alkaline, which is the general characteristic of the variety of albumin known by the name of histones. Miescher, the learned chemist of Basle, who had noticed this basic albumin when working on the Rhine salmon, gave it the name of protamin. This is the substance submitted by Kossel to analysis in preference to the albumin of egg, so dear to the chemists who had preceded him. The disintegration of this molecule, instead of giving the series of bodies obtained by Schützenberger, gave but one, a real chemical base, _arginin_. At the first trial the albumin examined was reduced to a simple crystallizable element. The conclusion was obvious. The protamin of salmon is the simplest of albumins. To form this elementary proteid substance a hexonic base with water is all that is required. Continuing on these lines other male generating cells were examined and a series of protamines constructed on the same type was found, and these albuminous bodies proved to be formed of a base or mixture of analogous hexonic bases: arginin, histidin, and lysin—all bodies closely akin in their properties and entirely belonging to the physical world. Once aware of the existence of this fundamental nucleus, chemists found it in the more complex albumins where it had been missed. It was found in the albumin of egg hidden under the mass of other groups. It was recognized in all animal or vegetable albumins. The nuclei of Schützenberger may be missing. Hexonic bases are the constant and universal element of all varieties of albumins. They prevail in the chemical nucleus of the albuminous molecule, and perhaps as is suggested by Kossel, they may form it exclusively. All the other elements are superadded and accessory. The essential type of this molecular edifice, sought for so long, is known at last. _Conclusion._—To sum up, the chemical unity of living beings is expressed by saying that living matter, protoplasm, is a mixture or a complex of proteid substances with an hexonic nucleus. CHAPTER IV. THE TWOFOLD CONDITIONING OF VITAL PHENOMENA. IRRITABILITY.