No. 6.— The Nervous System of Nereis virens Sars. A Study 
in Comparative Neurology. By J. I. HaAmMAKeER.1 
CONTENTS. 
Page Page 
Meroauction ... « « « « . . 89 e. Peripheral Fibres . . . 105 
Methods... ...- «.. . 90|PartIl Dis@ission .... . 106 
eee Description ©. . . « . QOL), 1. Topography. .. ..:°. 106 
aeunoeraphy. . s . . - . SL *'2: Protective Tissue . . .. : 107 
a, Brain: +. « « O23) Brainy «o's sercweostees ASS 
b. Sub-cesophageal eueglion 93| 4. “Mushroom Bodies ” ee es 
ce. Typical Body Segment . 94] 5. Optic Ganglion .... . Ill 
d. Parapodial System. . . 95] 6. Ventral Nerve Cord. . . . 112 
maeerotective Tissue <« <i). . 961) % Centrosomes .. . . .. 112 
oeebrsin’. c « eeraicees? Olt 1S). Nerve HiDreskia wo. ew Lhe 
4. Ciliated Gmnisve sae aness he 100 a: Giant Mibres' < a... IS 
5. Ventral Nerve Cord. . . . 100 b. FibresofSet A... . 115 
Sw Nerve Hibres: «20... ., » 102 c:} Hibresof'Set B : = . . 116 
a Giant Hibres.. 5 . . = 102 d. Fibres of Sev . . . . 118 
ecctiores OF Seb A < 5... 108|Summary .°. 1... . . « +- 8 
ec. Fibres of SetB . . . . 104) Bibliography . . Ses ae 
d. Fibres of SetC . . . . 105! Explanation of Plates rtp 
INTRODUCTION. 
ALTHOUGH so much has been written on the nervous system of repre- 
sentatives of all the chief groups of the metazoa, we are as yet far from 
thoroughly understanding the action of the myo-neural mechanism of 
any animal. It is true, much light has been thrown upon the subject 
during the last decade through the use of the newer methods of investi- 
gation; but the many valuable facts that have been established are as 
yet so disconnected, that they can scarcely be said to be more than sug- 
gestive. In no case has the myo-neural system of an animal been at all 
completely worked out. In the higher animals the complexity of this 
system makes such a task almost impossible. At any rate, the most 
1 Contributions from the Zodlogical Laboratory of the Museum of Comparative 
Zodlogy at Harvard College, under the direction of E. L. Mark, No. XCI. 
VOL, XXXII. — NO. 6. i 
