466 University of California. Publications in Zoology [Vol.22 



supply. That of the caeca! typhlosole has been described above. A 

 small branch from the posterior aorta (pi. 22, fig. 1) supplies the 

 gastro-intestinal typhlosole at the bend of the intestine where the typh- 

 losole ends. Another small branch (or., pi. 24, fig. 11) goes to the 

 dorsal edge of the posterior hepatic orifice, probably supplying the 

 gastric typhlosole. 



THE DIGESTION OF WOOD 



The extent to which Teredo digests wood and the conditions under 

 which this digestion proceeds have an important bearing on the 

 success or failure of methods of wood preservation, aside from their 

 purely biological interest. Physiological and chemical evidence that 

 wood is digested to a considerable extent has been accumulated 

 (Harrington, 1921; Dore and Miller, 1923). The caecum with its 

 large typhlosole has generally been accepted as good evidence for the 

 digestion of wood, and the fact that a third or more of the blood 

 leaving the heart is led directly through this typhlosole makes it 

 certain that we have here a very effective organ of absorption. 



Evidence of the digestion of cellulose was found in the serial 

 sections that were prepared during the course of the present investi- 

 gation. The contents of the stomach, caecum, and intestine usually 

 remained in place in the sections. This can be seen in the photomicro- 

 graphs on plate 24. When sections were stained with Delafield's 

 haematoxylin, the wood fibers in the stomach and in the caecum took 

 the stain, while those in the intestine did not to any appreciable degree. 

 Since Delafield's is a selective stain for cellulose (Molisch, 1921). it is 

 evident that at least a part of the cellulose had been removed from 

 the wood fibers during their stay in the stomach and caecum. Unfor- 

 tunately the difference in color does not show in the photomicrographs. 



