esterly: eucalanus. 29' 



with iron-haematoxylin (Plate 2, Fig. 23), or in jNIallory's connective- 

 tissue stain (Plate 5, Figs. 44, 50). Even the granules of the c}to- 

 plasm take part in the general radiate arrangement. It is also very 

 plain that the contents of the cells are more densely aggregated nearer 

 the basal plates than toward their distal ends (Plate 5, Fig. 50). 



It is difficult to say whether this striation is in any way related to the 

 ''Streifung" which Hesse notes in connection with the "Stiftchen- 

 saum." But in my opinion the denser condition of the cell contents, 

 as well as the striated appearance in the retinal cells, is an expression 

 of the greater secretory activity of the cells in that region, the product 

 of which is shown in the basal plates, since the latter must be regarded 

 as products of the retinal cells, for there are no others from which they 

 can reasonably be derived. 



Such striations are strikingly shown, also, in the cells of the digestive 

 tract in Eucalanus (Plate 4, Fig. 52), where it is very unlikely that they 

 can be regarded as due to the presence of end fibrillae of nerves spread- 

 ing out into the cell contents. This condition of the digestive-cells, 

 I believe, is strictly in line with that shown by jMark('76) to exist in 

 the cells of the salivary glands of certain Coccidae. 



The true character of the neurofibrillae is shown in such a drawing 

 as Figure 49 (Plate 5), where, in the cells of the ventral eye, the struc- 

 tures that I take to be the neurofibrillae of the axis cylinders are shown 

 as rather heavy, beaded bodies (». fhrl.). These lie at a very low 

 focus in the section (a fact which cannot be expressed in the drawing), 

 and are in all likelihood parts of the two nerve fibres shown in a cor- 

 responding position in Figure 45. In the left lateral eyes (Fig. 49, 

 ocJ. s.) there are two nerve fibres which may be seen to be directly 

 connected with similar structures. In the right eye one such is shown. 

 The nerve endings when shown in their entire extent (as I believe is the 

 case in Figure 49, n. fhrl.) stand out with remarkable clearness from 

 the rest of the cell, and they take a tint almost precisely the same 

 as that of the nerve fibres outside the cells. It is not unlikely that 

 some of the granular appearance in the basal parts of the cells of the 

 eyes is due to the presence of the beaded nerve-terminations. This is 

 indicated rather strongly in the right lateral ocellus shown in Figure 

 49. 



As far as my observations go, therefore, the median eye of the 

 Copepoda does not resemble the eye of the flatworms in having the 

 recipient ends of the nerves turned toward the pigment, nor in the 

 character of the nerve ending, since it does not possess a "Stiftchen- 

 saum" in the sense in which Hesse uses the word. It might be said 



