Haeckel and Gegenbaur set the fashion for phylogenetic speculation, and up to the middle 'eighties, when the voice of the sceptics began to make itself heard, the chief concern of the younger morphologists was the construction of genealogical trees. The period from about 1865 to 1885 might well be called the second speculative or transcendental period of morphology, differing only from the first period of transcendentalism by the greater bulk of its positive achievement. It must be remembered that the later workers (at least towards the end of this period) had immense advantages over their predecessors in the matter of equipment and technique; they possessed well-fitted laboratories in the university towns and by the sea; they had at their command perfected microscopes and microtomes; while the whole new technique of microscopical anatomy with its endless variety of stains and reagents made it possible for the tyro to confirm in a day what von Baer and Mueller had taken weeks of painful endeavour to discover.[386] But the democratisation of morphology which followed upon the facilitation of its means of research left an evil heritage of detailed and unintelligent work to counterbalance the very great and real advances which technical improvements alone rendered possible. This period of rapid development, which set in soon after the coming of evolution and multiplied the concrete facts of morphology an hundredfold, may for our present purpose be conveniently divided into two somewhat overlapping periods, of which the second may be said to begin with the enunciation by Haeckel of his Gastraea theory. Within the first period fall the evolutionary speculations associated with the names of Kowalevsky, Dohrn, Semper, and others; the characteristic of the second period is the preponderating influence exercised upon phylogenetic speculations by the germ-layer doctrine in its two main evolutionary developments, the Gastraea and Coelom theories. In the first period we might again distinguish two main tendencies, according as speculations were based mainly upon anatomical or mainly upon embryological considerations, and it so happens that these two tendencies are very well illustrated by the various theories as to the origin of Vertebrates which began to appear towards the 'seventies. We shall accordingly, in this chapter, consider very briefly the history of the earlier views on the phylogeny of the vertebrate stock.