The question was purely rhetorical. Every Martian knew it was the ability to change form at will. "This trait is of course due to superior mental ability and training. But even for us there has been a definite limitation, caused of course by residual atavisms ... atavisms which we must, and some day will, extirpate completely from our glorious race." Excitement overcame his mental control and for a moment he became completely invisible. He frowned mentally as he caught a tittering reaction from some individual in the audience. Invisibility, too, was an aspect of shape adaptation, of superiority, though because it no longer served a useful purpose it had come to be regarded with suspicion as an atavistic trait. This was particularly true of the involuntary invisibility which sometimes accompanied high emotional tension. A powerful and growing school of thought even considered emotions themselves as atavisms. A human audience would have fidgeted as Yark recounted in minutest detail the processes by which Erg, to whom had been granted the honor of becoming the first Martian to visit another planet, had been reduced to the lowest common denominator of Martian consciousness, a mass of specialized but undifferentiated cells. And Yark, Yark of the Council of Great Brains, had been in charge since the very earliest stages of Erg's embryohood. "This reduction," Yark declared, "has been possible only by complete elimination of all atavistic traits. Even latent ones." He told with obvious satisfaction of Erg's unprecedented perfect zero score on the famous Yark Anti-Atavism Test. "Erg will remain in full telepathic contact with me," the Great Brain continued. "Immediately following the landing there will be a period of quiescence, necessary to allow Erg to adjust himself to his new environment. During this period he will be able to gather and retransmit mental impressions from any intelligent creatures nearby--providing of course any such creatures exist upon this barbarously un-Martian planet--but his individuality will remain passive. "Following the period of quiescence, differentiation of cells will take place. Erg will then be a full-fledged Martian and will explore the entire planet. After that, who knows what vistas of greatness lie ahead? "In his present form only I, his mentor and creator, can retain contact. But you honored Martians will be allowed to become attuned to my brain and thus receive Erg's reports." He paused and held aloft a transparent cylinder. The Martians stirred with interest. They were all greatly impressed, although Erg resembled nothing so much as a pot roast in a jar. They had never heard of a pot roast. "We shall now dispatch Erg upon his epochal journey." * * * * *