Triplanetary was first serialized in Amazing Stories in 1934. After the Lensman series became popular, Smith took his Triplanetary story and turned it into the first of the Lensman series, using it as a prequel to give the back story for the protaganists in the Lensmen series. He added 6 new chapters, doubling it in size and it's really a different book from the serialized novel, being published 14 years after the first. It was put into Gutenberg just last year.

The novel covers several episodes in an eons-long eugenics project of the super-intelligences of the Arisia. This alien race is breeding two genetic lines to become the ultimate weapon in Arisia's cosmic war with their arch enem...