George L. Streeter 27 



and uniform size. It is increased in the region supplying the wing 

 musculature. A relatively greater increase would he expected in flying 

 hirds, the comparison of the ostrich with one of the large hirds of prey 

 would he interesting. When we go farther caudalwards and come to 

 the increase of the primary apparatus corresponding to tlie massive leg 

 musculature we find a great tumor-like enlargement, or Locomotor Brain, 

 which demonstrates, as perhaps nowhere else in the animal kingdom, the 

 close interdependence hetween a section of the central nervous system and 

 the area innervated. 



An interesting feature of the lum1)o-sacral enlargement is the man- 

 ner in which the neuromeres are marked off on the ventral surface of 

 the cord by the hill-like prominences, calling to mind the segmental 

 appearance presented by the well-known Trigla cord. 



The marked development of the sinus rhoml)oideus offers favorable 

 conditions for the study of this characteristic feature of the bird cord. 

 We are enabled to contribute some facts as to the nature of the peculiar 

 tissue with which this sinus is filled. 



In studying the finer structure of the cord, the grouping of the cells 

 into defined columns could be followed, some of which extend through- 

 out the length of the cord. Two particularly interesting groups were 

 found, one limited to the thoracic region in the posterior grey commis- 

 sure, the other a group of " giant " cells occurring in the lumbo-sacral 

 and cervical enlargements. The segmental groups of cells or nuclei oc- 

 curring on the periphery of the cord, which have recently been the sub- 

 ject of much attention, are found in the characteristic way, and more- 

 over are here present as macroscopic structures. 



Our material was not such as to allow us to say anything of especial 

 importance concerning the fibre tracts that would be new for the bird 

 spinal cord. In this direction we can only look for advancement from 

 experimental work such as was begun by Friedlander in this laboratory. 

 Attention, however, is to be called to the short course taken by the 

 fibres in the dorsal funiculi, and to the small proportion of these fibres 

 that eventually reach the higher centers through this path directly. 



