26 BULLETIN OF THE 



merits." Iijima ('84, p. 389) also saw "eine senkrechte Streifung." 

 Lang ('81, p. 196, and '84, p. 109) speaks of it as a " euticulaanliches 

 Epithel " with flattened nuclei which it was difficult to see, and Minot 

 ('77, p. 426) gives to it a well defined basement membrane. It is 

 obvious from the description that I have given of the young pharynx 

 that the outer layer, though ultimately much modified in appearance, 

 is nevertheless an epithelial layer. 



I could not demonstrate the presence of a cuticula with pore canals 

 such as has been described by Iijima ('84, p. 390) ; neither could I dis- 

 cover anything answering to the nerve plexus described for other forms, 

 nor could I detect any nerve tissue. From the automatic movements 

 of the isolated pharynges, one would expect to find a complicated system 

 of nerves, and perhaps one or more ganglionic centres. 



In the mature pharynges the radial muscle fibres run from tne outer to 

 the inner epithelium, to both of which they are attached by their finely 

 branched ends (Figs. 12 and 1G). These muscles no doubt act antago- 

 nistically to the broad band of circular muscles in dilating the lumen of 

 the pharynx, and by means of these two systems the peristaltic motions 

 displayed by the pharynges are accomplished. Between the radial fibres 

 there is a network of connective-tissue cells, and in the outer half of this 

 middle zone occur the salivary ducts (Figs. 12 and 1G, dt. sal.), which 

 run the whole length of the pharynx and open at the edge of its lip. In 

 the meshes of the connective-tissue network are seen fine granulations; 

 these spaces are undoubtedly in communication with the pseudocode 

 of the body mesenchyma, and it is to the coagulation of the perivisceral 

 fluid which has made its way out into the tissues of the pharynges that 

 is due the granular appearance seen. 



I have little to add to what has been written concerning the histology 

 of the intestine, my observations agreeing in the main with those of 

 Iijima. The structure is the same in the principal tracts and in the 

 smaller branches ; there are no differentiated gland cells. During the 

 periods of most active digestion the intestinal cells are filled with highly 

 refractive oil-like globules, of different sizes (Plate IV. Fig. 43), — the 

 food matter absorbed by the cells. In this condition the cells are large, 

 and protrude into the lumen, so that in the smaller branches of the 

 intestine the latter has entirely disappeared. The contents of the cells 

 are eventually absorbed by the neighboring tissues, and the intestinal 

 cells themselves then appear vacuolated. 



I have not been able to trace out the course of the excretory canals. 

 Although I have endeavored many times to study them, I have never 



