10 W. BLAXLAKD BENHAM. 



or less abundance ; x and I have sometimes noticed an apparent 

 division of this cavity by a transverse partition, the granula- 

 tions having a slightly different appearance in the two sides of 

 this partition (fig. 14). Moreover in this same series of 

 sections, as also in sections stained with Weigert's picro- 

 carmine, the blood in undoubted blood-vessels, such as hepatic 

 vessels, dorsal and subendostylar vessels, takes on a character- 

 istic deep red colour deeper than the tint taken by the 

 skeletal tissues, so that I am able most definitely to state that 

 there are three blood-vessels traversing the tongue 

 bar, not two, only as Spengel and Boveri believed (c.f. fig. 1 

 with figs. 7, 8). 



Of these three vessels, two occur always at opposite ex- 

 tremities of the septal membrane, in the triangular spaces 

 already mentioned ; the third lies inside the rod, and may 

 be called the skeletal vessel. Usually it has the position 

 represented in fig. 1 in the chief canal of the rod, but it does 

 not appear to fill this canal; lean generally detect a 

 slight space around it. This may, of course, be due to shrinkage 

 of the clotted blood ; but the apparent existence in some cases 

 of a partition (see fig. 14 and the explanation of it) favours my 

 view, as also does the condition of things represented in fig. 13, 

 where the vessel is passing out of the cavity, that this cavity 

 of the rod is coelom, which contains a blood-vessel. 

 This view is further strengthened by the fact that, both in my 

 hsematoxylin preparations (where the blood-vessels are not 

 evident) and in my cochineal sections, I have detected flattened 

 nuclei pressed against the inner surface of the rod, as repre- 

 sented diagrammatically in fig. 1, and accurately drawn from 

 the object in fig. 13. This, I may say, has not been an occa- 

 sional occurrence, but can be seen in many accurately trans- 

 verse sections of the bar. 



In some of the variations from the normal the rod presents 

 a small cavity about midway between the main canal and the 

 apical notch (figs. 13, 14), and this cavity is usually connected 



1 Spengel mentions the presence of finely granular material in the canal of 

 the hollow rod (loc. cit., p. 278), 



