MORPHOLOGICAL STUDIES. 
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(No. 20), and in a certain sense Dohrn and others, regard 
the head as a specially modified portion of the trunk, and, 
as is well known, Gegenbaur (No. 20) considered that 
certain of the cranial nerves could be reduced to spinal nerves. 
His present position with regard to recent researches is defined 
more or less clearly in his recent paper (No. 21). I cannot 
now enter into a criticism of that — the limits of my space 
forbid it, — and, as far as possible, I have endeavoured to shut 
speculative matter out of this research. 
Dohrn (No. 13, p. 471) has formulated his conclusions as 
to the relations of the spinal and cranial nerves and ganglia in 
the following passages : — 
“ Die Hirnnerven haben diejenigen Leitungsbahnen ver- 
loren, welche die Urwirbel und deren Derivate iunervirten ; sie 
haben aber in Folge der ausserordentlichen Yergrosserung 
und Complicationen der visceralen, i. e. ventralen Theile des 
Kopfes um so mehr gewonnen und sind durch die vielfaclien 
Verschiebungen der beziiglichen Theile in ihrem Yerlaufe sehr 
verwickelt geworden. 
Die Spinalnerven ihrerseits haben am Rumpfe in ihren 
visceralen Verrichtungen Verschiedenes verandert( — auf welche 
Weise soli spiiter dargestellt werden — ,) haben aber durch die 
Entwickelung der Kbrper — und Extremitaten — Musculatur 
im Umfang im Allgemeinen nicht vermindert, und sind in 
gewissen Sinne weniger modificirt, als die Cranialnerven. 
Am Schwanz dagegen haben sie durch die Einbusse der 
gcsammten Yisceralpartien die starksten Verluste erlitten und 
sind dort demgemass am wenigsten complicirt.” 
While there are some points in the above statements with 
which I can express my agreement, my standpoint is more on 
Froriep’s side than on that of Dohrn. For a general survey of 
Froriep’s views I must refer the reader to that investigator’s 
recent utterances (No. 19, p. 833, et seq.). 
I agree with Professor Froriep that at present we cannot 
see much beyond the primitive separation of the Vertebrate 
body into two sharply-defined regions, — a respiratory region 
the head, and a locomotive (and digestive) region the trunk- 
