In the single state the canal remained most of the time. It then underwent a chrysalid stage of confusion to emerge of a sudden into a perfect pair. Furthermore, he noted the times at which the pairing took place, to the formulating of a law in the case—derived from the observations of more than one opposition. His law was that the gemination occurred, on the average, three months (ours) after the summer solstice of the northern hemisphere, lasted four to five months, then faded out to begin afresh one month after the vernal equinox of the same hemisphere and continue for four months more. Expressed in Martian seasonal chronology, the periods would be about half as long. At certain times then the most pronounced specimens of doubles showed obstinately single, while the periodic metamorphosis that transformed them into duplicates was timed to the changes of the planet’s year. Gemination, then, was a seasonal phenomenon. Advance in our knowledge of the phenomenon since Schiaparelli’s time, while still showing the thing to be of seasonal habit, has changed our conception of it. It now appears that in some cases certainly, and possibly in all, the dual aspect is not a temporary condition, but the differing pronouncement of a permanent state, the fact of gemination so called being confined to a filling out of what is always skeletonly there. As the canals have come to be better seen, the three stages of existence have in some cases become recognizable as only different degrees in discernment of an essential double condition; the single appearance being due to the relative feebleness of one of the constituents and the confused showing to the weakness of both, which are then the more easily blurred by the air waves. In certain canals the last few oppositions, 1901, 1903, and 1905, have disclosed this unmistakably to be the case, as with the Phison and Euphrates, for example. With them the double character has been continuously visible, appearing not only when by Schiaparelli’s law it should, but at the times when it should not; only on these latter occasions it was harder to see, whence the reason it was previously missed. So that further scrutiny, while in no sense discrediting the earlier observations, has extended to them some modification, and disclosed the underlying truth to be the varying visibility, the thing itself, except for strength in part or whole, persisting the same. Improvement in definition has lowered the see-level to revelation of continuous presence of the dual state. It is only on occasion that the improvement is sufficient for the thing when at its feeblest to loom thus above the horizon of certainty; yet at such moments of a rise in the seeing it is enough to allow it to be glimpsed. Thus it fared with the Adamas at the opposition of 1903, with the Gigas, and with many another in years gone by. Separation has come with training and generally in the case of the wider doubles, which leads one to infer that ease of resolution is