The Journal of Comparative Neurology Volume 6 (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: PRELIMINARY NOTES ON THE CRANIAL NERVES OF CRYPTOBRANCHUS ALLEGHANIENSIS. J. H. Mcgregor, B.Sc., University Fellow in Biology, Columbia University. The present communication is by no means a complete description of the cranial nerves of Cryptobranchus, but is merely a somewhat cursory sketch of the distribution of most of the more important rami. It was the hope of the writer to have completed before this time a study of the brain and cranial nerves of this amphibian, working out the nerve components from serial sections, but the difficulty in obtaining embryonic material for sectioning has so delayed the work that it has been thought best to present a brief preliminary account based almost entirely upon dissections of adult animals. Recent researches on cranial nerve components render it possible to determine, even by dissection, some points of importance in nerve homologies, though, of course, reconstruction from sections will be necessary to ascertain the more intimate relations of the components. In general, no attempt has been made in the present paper to trace the relations between nerve-roots and the ultimate rami. So far as possible the writer has endeavored to indicate homologies with other amphibians, basing the comparisons mainly upon recent investigations on Rana, Amblystoma and Salamandra. Netvus olfactorius.?This nerve is somewhat peculiar in Cryptobranchus from the fact that it divides into numerous branches before leaving the cranial cavity. Within the cranium these branches extend cephalad in two large bundles on each side, giving each olfactory nerve the appearance of being double. Nervus opticus.?The optic is very similar to that of uro- deles in general. There is a slight vestige of a lumen at the base of the nerve. The nerves of the eye...