44 



CONAEIO-HYPOPHYSIAL TRACT. 



the myelon, the surface of the body next to which those 

 nerve-centres are respectively extended must be the same. 

 If such surface be turned dov^nward in the ordinary station 

 and progression of an Insect, the cohimns on v^hich the 

 sensory gangUons are formed will be " inferior while in 

 Vertebrates, according to the position in which the body 

 may be carried, the ganglionic or sensory columns will 

 be " superior " in the beast and " posterior " in the man. 

 Terms, therefore, defining aspect and position independent 

 of the accident of limb-direction, should be acceptable : 

 "neural" and " hasmal " are as applicable to parts as to 

 wholes. 



A heart, whether compact or elongate, has a surface looking 

 toward the neural aspect, and a surface with an opposite 

 aspect. One may predicate of the haemal side of a " heart " 

 or " dorsal vessel " whether it be at the fore side of the body 

 (in a man), or at the under side (in a beast), or along the 

 upper side (in an insect). So likewise with regard to the 

 nervous axis : Newport's sensory ganghons in that of the 

 Insect are developed in and from the cords on the " neural " 

 side of such axis, as they are in the neural " columns of 

 the Vertebrate myelon, as distinguished from the " hsemal " 

 columns. 



Developmental researches may gain by such appreciation. 

 The admirable Investigator whose recent loss Morphologists 

 deplore, thus writes : — " The embryo of Feripaim shows 

 what was once part of a continuous slit running nearly its 

 whole length ... " it at first leads into the ahmentary 

 canal, like the neurenteric canal of the vertebrate embryo ; 

 but this communication is closed prior to the appearance of 

 the first rudiments of the ventral nerve-cords"*. 



* O'j). cit. 



