MORPHOLOGICAL STUDIES. 
155 
Introduction. 
Nearly three years ago I published (No. 6) iu the pages of the 
'Quart. Journ. of Micr. Sci.,’ some researches on the morphology 
and development of the so-called "organs of the lateral line,” 
which appeared to me then, as now, to be in reality special 
branchial sense organs. When those researches were first 
undertaken in Professor Semper’s laboratory (No. 4), it was 
far from my intention to investigate the development of the 
cranial nerves and ganglia, but in the course of the work it 
soon became obvious that the thorough study of those sense 
organs could only be accomplished by including the cranial 
nerves and ganglia in the sphere of the observations. And, 
indeed, almost the first Elasmobranch embryo examined 
showed unmistakeably that the cranial ganglia and the sense 
organs of the lateral line are intimately associated in their 
morphology and development. 
The researches then published include also attempts to 
liomologise the sensory portion of the nose and ear with the 
sense organs of the lateral line. And it is partly with the 
wish to get more light on this question that last year I under- 
took the investigation of the first beginnings of the cranial and 
spinal ganglia. Two papers — very different in their stimulat- 
ing effects — urged me all the more to a thorough study of 
these problems. 
In a short notice Dr. van Wijhe (No. 61) — whose right to 
an opinion on this matter is unquestionable — considered his 
researches on Ray embryos entitled him to combat my pre- 
viously published views of the nature of the nose. I give in 
the following lines van Wijhe’s own words. 
He says : “ Die Auffassung nach welcher der Olfactorius ein 
8egmcntaler Nerv sei, ist ueulich wieder von Dr. Beard ver- 
treten. Er griiudet dieselbe auf die Theilnahme der Epidermis 
an der Bildung des lleichnerven und seines Ganglions, wie 
dies auch bei den Nerven der Seitenorganen der Fall ist und 
glaubt die Reichgruben seien deshalb den Seitenorganen und 
der Olfactorius den Nerven dieser Orgaue homolog. 
