100 ON THE MOKPHOLOGICAL CONSTITUTION OF 



plex haemal arches into an upper and a lower series, I am 

 compelled on philosophical grounds to deny that the sub- 

 division of a " pleurapophysis" or of a " hsemapophysis," is 

 beyond the range of morphological law ; or that morphology 

 and teleology are distmct in the sense that the latter principle 

 provides for what the former is insufficient. Morphology and 

 teleology are merely opposite, because, in the present phase of 

 science, necessary anthropomorphic aspects of the same Divine 

 principle evinced in the laws of organisation. 



Until, then, we know more than we do at present of the 

 laws which regulate the number of " centres of chondrification 

 and ossification," and until the constitution of the inferior 

 vertebral arches in the embryo and adult series has been more 

 fully analysed, I cannot give my assent to the expression for a 

 haemal arch involved in Professor Owen's osteological doctrine. 



I must here allude to a point which does not appear to 

 have attracted that attention which it deserves. None of the 

 haemal arches of the head inclose the haemal axis. If we are 

 to consider the so-called median and lateral frontal with the 

 superior maxillary lobes as visceral laminae, then, as such, 

 they have no primordial relation with the haemal axis, which, 

 under the form of the cardiac-branchial tube, extends forward 

 as far only as the so-called " first visceral lamina." After the 

 haemal arches have been formed in " the first and other 

 visceral laminae," usually so called, of the head, the hajmal 

 axis is found to be excluded from them. It is in consequence 

 of this remarkable developmental arrangement that the heart, 

 branchial artery, and its branches, in the fish and amphibia, 

 are situated below^ and external to the skeleton of the bran- 

 chial apparatus. 



Before pointing out what appear to me to constitute cer- 

 tain of the developmental conditions on which this peculiar 

 relation of the haemal arches of the liead to the haemal axis 

 is dependent, I must direct attention to another relation, in 



