THE GASTRAEA THEORY, ETC. 147 



against there being any condition between ontogenesis and 

 phylogenesis.^ He seeks, instead of this, to explain the onto- 

 genetic phenomena in the most superficial manner by bend- 

 ings, foldings, &c. &c., without being able to assign any 

 further ground whatever, any operative cause, for these 

 " mechanical" developmental processes. The useless display 

 of mathematical formula which His makes cannot thereby 

 hide the want of a true causal principle, nor lend any worth 

 to his paradoxical fancies. As I have already explained in 

 the * Biology of the Calcareous Sponges' (p. 4:12), such fancies 

 appear only as humorous illustrations, not fit for earnest 

 refutation ; at the same time these big blunders prove how 

 necessary, for the workers in the difficult field of ontogenesis, 

 is the finding one's position in the province of comparative 



' His ' Untersucbungen iiber die erste Anlage des Wirbelthierleibes,' 

 Leipzig, 1868, pp. 211 — 223, and elsewhere. Very characteristic of bis con- 

 ception of biogenesis are his general remarks on the subject in his dis- 

 course, ' Ueber die Bedeutung der Entwickelungsgeschichte fiir die Auffas- 

 sung der orgauischen Natur' (Leipzig, 1870, p. 35). His considers it 

 necessary to guard the claims of the history of individual development 

 against the overwhelming power of the Darwin intuition," and thinks " that 

 the whole of the arguments derived from morphology, or the history of 

 development, in favour of Darwin are not for tliis reason of sufficient 

 strength, because they by no means require, as the immediate consequences 

 of the physiological principles of development, the explanation of the widely 

 circuitous genealogical relationship. If the genealogical relationship of 

 organic existence actually undergoes such expansion as enables it to take in 

 everything which the tiieory undertakes to sustain, so must all typical and 

 developmental coincidences appear as quite indisputable consequences (! !). 

 To reason a posteriori from the typical and developmental coincidences to a 

 blood relationsiiip, rather than more practically to acknowledge the demon- 

 strated growth, might, on a first glance, but not Ioniser, be allowed. Such 

 a prosj^ect discloses the different aims of development like empty realisations 

 of a mathematically defined circle." This explanation of His refutes itself 

 ou accurate examination. But to understand the perfect baselessness of 

 his point of view, one need only look a little closer into the "physiological 

 principles of development" by which His tries to "illustrate mechanically" 

 the ontogenetic events; to eliminate the theory of descent and to deny the 

 connection between ontogenesis and phylogenesis. Here it needs but the 

 quoting of a single example — so cliaracteristic is it — to show the style and 

 manner in which His thinks to prove the principles of morphology to be 

 necessary consequences of a nicchanical developmeut {loc cit., p. 3l). His 

 says : " How simple the homology of the fore and hind limbs appears when 

 we know tiiat their first appearance is determined by the crossing of four 

 folds encircling the body, like the four corners of a letter (!). How clear 

 also becomes the once difficult comparison of the anterior with the posterior 

 extremities of the body, when we also here go back to the primitive 

 fact tliat the head as well as the posterior extremities of the body finds 

 its termination in an unflapped fold, and that all the mechanical conditions 

 which accompany such an unfiupped fold must make their appearance in 

 front as well as behind." It would be difficult, indeed, in the whole range 

 of the literature of morphology, to find an example of an equally crude and 

 superficial explanation of a morphological relationship. 



