Geo. C. Price 121 



gatlieved from Fig's. '2 to S, representing a continuous series from the 

 middle of one neplirotome to the middle of the next, but the segmental 

 character of the solid portion of the neplirotome is not so apparent. This 

 is because the nephrotomes in adjoining segments come into direct con- 

 tact with each other, and some part shows in every section, just as the 

 segmentally arranged myotomes appear in every section. However, the 

 nephrotomc becomes smaller towards the end than it is in the middle, 

 and the point where two nephrotomes come together (Fig. 5) can quite 

 easily be detected by the smaller size of the section and the indistinct- 

 ness of the outline. 



In order to gain an idea of the appearance of a sagittal section through 

 the nephrotomes, camera lucida drawings were made of all the sec- 

 tions in three segments, and from these Fig. 9 was reconstructed on milli- 

 meter paper. 



The proportions are here fairly accurate, but it was a question whether 

 the nephrotomes should be represented in 

 close contact with one another, or as hav- 

 ing a slight space between them. It is pos- 

 sible, though not probable, that an actual fig. 9.-a reconstruction of a 



... I J- • 1 . ^ L- -L sagittal section through throe neph- 



Saglttal section might even show continuity rotomes, made on millimeter paper. 

 , , T . , T , nc, uephroctel. 



between adjacent nephrotomes. 



The posterior end of one nephrotome and the anterior end of the 

 next (Figs. 4 to 6 and Fig. 9) may be looked upon as forming a sort 

 of short, discontinuous rod. This would be more apparent in a frontal 

 than in a sagittal section. This remark is made because later they form 

 an actual rod extending from one nephrotome to the next, and giving 

 rise ultimately to the greater part of the segmental duct between con- 

 secutive tubules. 



What has been said thus far in regard to the nephrotomes applies to 

 those representing a middle state of development, those toward the an- 

 terior end being in some respects more advanced, and those toward 

 the posterior end less advanced. As an example of the latter we may 

 take the one in the sixty-eighth segment, a section through which is 

 represented in Fig. 10. Here the nephrotome is attached to the myo- 

 tome, although a well marked constriction has appeared between them. 

 There is a very small nephrocoel, but the greater part of the centre of 

 the nephrotome consists of non-nucleated protoplasm which is continuous 

 with the non-nucleated protoplasm of the myotome. There is no dis- 

 tinct boundary between the nephrotome and the sclerotome. On this 

 side the last nine nephrotomes are attached to the myotomes, and a few 

 just in front have somewhat the appearance of having been torn away. 



