Literary Notices. liii 



carefully studied and its physiological significance worked out. The 

 theory of vision adopted is that of Max Schultze and Grenacher, that 

 the rhabdome is the perceptive organ of the retina. The experiments 

 to determine the character of the image thrown upon the retina seem 

 to have been more carefully planned than those of the previous observ- 

 ers and are regarded as important in two respects. " They show that, 

 when the rhabdome is surrounded by pigment, its whole length can be 

 penetrated only by very strong light, though its distal end can always 

 be illuminated even by diffused daylight, and, secondly, they confirmed 

 the belief entertained by Miiller, Grenacher and Exner that the image 

 in the compound eye is a single upright one for the whole retina, whose 

 perceptive elements, the rhabdomes, receive each a single impression." 

 The optic ganglia, their decussations, and the optic nerve receive full 

 treatment. c. j. h. 



The Ciliary Ganglion.' 



Schwalbe, from comparative and embryological studies, came to 

 the conclusion that the ciliary ganglion is a root ganglion for the oculo- 

 motorius. The recent discovery that the cells of the cerebro-spinal 

 ganglia, except the acustic, are always unipolar with a single dichoto- 

 mous axis-cylinder, while the cells of the sympathic ganglia are multi- 

 polar, both in man and other mammals, has afforded an opportunity to 

 test decisively whether the ciliary ganglion is to be placed in the former 

 or latter category. In accordance with this principle, the author has 

 previously shown that the following cranial ganglia belong to the cere- 

 bro-spinal system, — g. Jugulare, g. cervicale n. vagi, g. petrosum n. glos- 

 sopharyn/rei, g. gejiiculi n. facialis, g. seminulare n. trigemini ; while the 

 following ganglia must be relegated to the sympathic system, — g. oti- 

 cum, g. spiienopalatimmi, g. submaxillare, g. ciliare. The ciliary gan- 

 glion was studied anew in the light of Schwalbe's results to determine 

 whether it might not be a mixed ganglion, but the result was only a 

 confirmation of the first conclusion. The application of the Golgi 

 method to the ganglion in the hands of Van Gehuchten gave negative 

 results and that author is inclined to regard it as a cerebro-spinal gan- 

 glion. Retzius has finally succeeded in securing adequate impregna- 

 tions and finds that his first result is fully confirmed again. The cells 

 are all of the multipolar sympathic type and there are no unipolar 

 cells among them. It appears that Michel has independently secured 

 the same results by the same method. 



* Retzius, Gustaf. Ganglion Ciliare. Biol. Unters., N. F., VI, 2-3, 1894. 



