442 MONTGOMERY. 



EXPLANATION OF PLATE XXV. 



Figs. 27, 28. Cerebratulus lacteus : ganglion cells IV (neurochord cells) from 

 the lateral chord. Sublimate, Del. haematoxylin + eosin. 



Fig. 29. Ibid. : ganglion cells III and IV, from the dorsal side of the lateral 

 chord. Sublimate, Del. haematoxylin + eosin. 



Fig. 30. /did. : portion of a horizontal, longitudinal section of the fibrous core 

 of the lateral nerve chord, from the middle body region. Sublimate, Del. haema- 

 toxylin + eosin. Obj. C, oc. 4. 



Fig. 31. /6zd.: Nuclei of ganglion cells IV. Sublimate. 



a, b, from the lateral chord. Ehrl. haematoxylin + eosin. 



c, d, of the right and left cells IV of the first brain pair. Del. haematoxylin 



+ eosin. 

 e, from the lateral nerve chord. Del. haematoxylin + eosin. 



Fig. 32. Ibid. : two contiguous ganglion cells IV, from the lateral chord ; their 

 respective nerve tubules not situated in the same plane. Sublimate, Del. haema- 

 toxylin -f- eosin. 



Fig. 33 a-^- Lineus gesserensis : outlines of the nerve tube of the lateral 

 nerve chord on four consecutive cross sections, to show its manner of branching. 

 Hermann's fluid. 



Fig. 34. Ibid. : outline of a cross section of the fibrous core of the lateral 

 nerve chord, to show the position of the nerve tubes {JV. T.). Hermann's fluid. 

 Obj. C, oc. 4. 



Fig. 35^-^. Cerebratulus lacteus: transverse sections of the right lateral 

 nerve chord. Obj. C, oc. 4. Sublimate, Del. haematoxylin + eosin. 



a, from the oesophageal region. 



b, behind the middle body region. 



c, from the anterior portion of the caudicle. 



Fig. 36. Lineus gesserensis : cross section of the fibrous core of the lateral 

 chord, in the anterior oesophageal region. Hom. immers. ^^, oc. 2. Hermann's 

 fluid, Ehrl. haematoxylin + eosin. In this, and in Figs. 37, 38, the appearance of 

 the preparation has been reproduced, the white lines representing the unstained 

 axis cylinders, and the dark ground (which should be of a bronze color) the deeply 

 staining, non-nervous substance of the fibrous core ; seen with this magnification, 

 this staining matrix appears nearly homogeneous. 



Fig. 37. Ibid. : cross section of the fibrous core of the dorsal brain lobe. 

 Hom. immers. j\, oc. 2. Hermann's fluid. (Cf. explanation of Fig. 36.) 



Fig. 38. Ibid. : frontal section of the fibrous core of the first ventral commis- 

 sure of the brain, a, the branch towards the dorsal lobe ; b, that to the ventral 

 lobe. Hom. immers. y\, oc. 2. Hermann's fluid. (Cf. explanation of Fig. 36.) 



Fig. 39. Ibid. : portion of a thin cross section of the fibrous core of the dorsal 

 brain lobe. Hom. immers. y^, oc. 4, tube extended. Hermann's fluid i hour, 

 Ehrl. haematoxylin + eosin. 



