46 J. H. ORTON. 



{Asijwmetron lucayanum) about which he observes: "As the animal is 

 small and translucent, the course of food and carmine granules may be 

 traced through most of the digestive tract. The strong current of 

 water setting into the pre-oral chamber seems to be controlled by the 

 longitudinal, ciliated ridges of Miiller's ' Raderorgan ' which pass for- 

 ward from the velum on the inside of each lateral wall of the pre-oral 

 chamber. Thus the carmine granules pass rapidly along these ridges 

 towards the velum, where they are turned inward towards the aperture, 

 mouth, at the centre of the velum. The granules pass along in strings 

 as if held together by a thin mucus ; once through the mouth they do 

 not pass out through the pharyngeal slits, but continue along the 

 median dorsal pharyngeal groove, the hyper-pharyngeal groove, still 

 adhering to one another in strings. In actual longitudinal and cross 

 sections these strings of granules may still be recognized in the ciliated 

 hyper-pharyngeal gToove. 



"This groove leads into what may be called the stomach, within 

 which the current of granules, or the granule containing mucous strand, 

 turns abruptly downwards and forwards as indicated in the above 

 diagram, yet does not enter the diverticulum, but, still under the control 

 of the active cilia lining the digestive tract, passes back again through 

 the centre of the stomach. It is now revolving rapidly in a constant 

 direction from right to left, and continues to do so throughout the next 

 division of the digestive tract, the first or larger section of the intestine. 

 In this part of the intestine the granules, diatomes, etc., collect into 

 clumps separated by the clear part of the continuous mucus-like 

 strand. In this region the intestinal epithelium is especially modified 

 in a zone that became very prominent when staining reagents are used, 



" The second, final and smaller part of the intestine, contains pellets 

 of detritus that become successively larger towards the anus, where they 

 have the form of elongated, not spherical, masses that are discharged 

 from the anus as the anal sphincter relaxes from time to time. The 

 mucous strand is here broken, the granular aggregates becoming isolated 

 from one another. These balls or pellets move along but slowly, and 

 give up the revolving motion seen in the first part of the intestine and 

 in the stomach. 



" The time elapsing from the addition of carmine to the water to the 

 discharge of carmine containing pellets may be much less than oiie 

 hour." ^ 



It will thus be seen that Andrews has described some of the processes 

 in the subsidiary method of feeding in the Bahamas Amphioxus which 



