OF LIVING MATTER 69 



More recent analyses tend to show that the molecular constitu- 

 tion of some proteids is, however, even much more complex than 

 that just given. Thus haemoglobin is a proteid in combination 

 with iron, whose presence in the blood corpuscles gives its 

 characteristic colour to this fluid. It has several times been 

 analysed by skilled chemists, and though their results have dif- 

 fered a good deal in details they have all shown it to be a 

 compound of extreme complexity. Pryer, for instance, found 

 the composition of haemoglobin to be as follows — 



C6ooH96oNi54FeiS30i7g. 



On the other hand, it seems equally clear from what has previously 

 been said (p. i8) concerning the free growth of Bacteria and 

 Torulae in solutions of ammonic tartrate in distilled water, that 

 proteids and even protoplasm can be formed readily enough from 

 C, H, O and N, together with the merest trace of sulphur or 

 phosphorus, which are commonly regarded as necessary and in- 

 variable elements in a proteid compound.' 



Most of these compounds whose molecules are so very complex, 

 are known to be capable of existing under very many different 

 isomeric modifications. Protein, for instance, according to Prof. 

 Frankland, is capable of existing under probably at least a thousand 

 isomeric forms ; and this, as we have seen, is the substance which, 

 in one state or another, enters so largely into the fabric of Uving 

 things as to be, above all else, the organisable material — the mole- 

 cules of which are, in some at present unknown way, built up so as 

 to form the still more complex body, protoplasm. The possibilities 

 of change and isomeric variation in this more complex product, 

 are further enormously increased by the common presence of 

 additional elements, which must be taken up by the proteids and 

 are thus brought into its composition. These common additional 

 elements found in protoplasm are chlorine, potassium, sodium, 

 calcium, iron, and magnesium. 



Three groups of proteids, varying in their solubility in water, 

 are known — as ' albumins,' ' globulins,* and ' vitellins ' ; while in 

 addition there are many very important bodies known as ' albu- 

 minoids,' which are derivatives, differing from the genuine proteids 



' Sir William Ramsay has been kind enough to analyse one of the solutions 

 of ammonic tartrate for me, and he reports that the "liquid contained an 

 excessively minute trace of sulphur, probably as sulphate ; but no phosphoric 

 acid could be detected by the molybdate of ammonium test." 



