correspond to one hundred and twenty isomeric combinations. We give below the number of possible compounds which result from simply altering the sequence, the form of combination remaining the same.
| The number of different units |
Number of resulting compounds, the sequence only being changed |
| 8 | 40,320 |
| 10 | 3,628,800 |
| 12 | 479,001,600 |
| 15 | 1,307,674,368,000 |
| 18 | 6,402,373,705,728,000 |
| 20 | 2,432,902,008,176,640,000 |
This enormous number of different compounds is solely produced by the manner in which the twenty elements follow one another. If hydrolysed, all these compounds would give the same elements to the same amount. These reflections may serve as a warning to those investigators who are inclined to infer the identity of particular compounds from the presence of the same elements.
Nor is it only the sequence of the individual units that needs to differ; for the mode of combination of the different compounds may also vary. The number of possible combinations is infinite. Again, the units are present in unequal quantities. Finally, one very important factor must be allowed for. No cell is composed of only one albumen particle, one carbohydrate, and one fatty substance; on the
