and therefore (taking its density as equal to that of water), a weight of
But of this total weight, the sulphur represents only
And if we divide this by the weight of an atom of sulphur, we have
According to this estimate, then, our little Micrococcus progrediens should contain only about 10,000 atoms of sulphur, an element indispensable to its protoplasmic constitution; and it follows that an organism of one-tenth the diameter of our micrococcus would only contain 10 sulphur-atoms, and therefore only ten chemical ãmoleculesã or units of protoplasm!
It may be open to doubt whether the presence of sulphur be really essential to the constitution of the proteid or ãprotoplasmicã molecule; but Errera gives us yet another illustration of a similar kind, which is free from this objection or dubiety. The molecule of albumin, as is generally agreed, can scarcely be less than a thousand times the size of that of such an element as sulphur: according to one particular determination47, serum albumin has a constitution corôÙreôÙsponôÙding to a molecular weight of 10,166, and even this may be far short of the true complexity of a typical albuminoid molecule. The weight of such a molecule is
Now the bacteria contain about 14% of albuminoids, these constituting by far the greater part of the dry residue; and therefore (from equation (5)), the weight of albumin in our micrococcus is about
If we divide this weight by that which we have arrived at as the weight of an albumin molecule, we have
in other words, our micrococcus apparently contains something less than 30,000 molecules of albumin. {42}
According to the most recent estimates, the weight of the hydrogen molecule is somewhat less than that on which Errera based his calculations, namely about 16ã₤ûã₤10ÿ£¢ã22 mgms. and according to this value, our micrococcus would contain just about 27,000 albumin molecules. In other words, whichever determination we accept, we see that an organism one-tenth as large as our micrococcus, in linear dimensions, would only contain some thirty