389 



"(woodcut: Clepsine A — B, see fig. 4) and its description and re- 

 ferences to it in the text are, I admit, bad; the three ducts, one 

 " branched and the other two unbranched, and the three nuclei should 

 "have been shown as they are represented in the diagram, but not 

 "the outlines of the smaller cells; nor should I have spoken of two 

 "cells as lying within the third" (1. c. p. 563—564). 



It is very strange that after such an acknowledgment of the real 

 cellular structure he did not take the trouble to verify my descrip- 

 tion of the structure of the ducts by accurately following a complete 

 series of sections. 



Puzzled by Mr. Bourne's persistency in admitting a single duct 

 thrice coiled up or recurrent, instead of three separate canals uniting 

 in the lower part, I applied myself again to the study of teased 

 preparations, taking great care to exactly follow his methods. 



These new researches gave fresh confirmation of my views, as 

 well as some indications as to the cause of some of Mr. Bourne's 

 misun derstandings. 



For instance, I am quite sure that the very long commissures 

 by which certain cells are united, have been taken by him, as well 

 as by Oso. Schultze, for separate portions of the whole organ, this 

 latter supposed to be unitubular and winding. That is what 

 several preparations like my fig. 6 have induced me to believe. 



This figure represents a large portion of the organ, as obtained 

 by dissociation with nitric acid. In c, c, c are shown several com- 

 missures, each of which is, in fact, traversed by a duct, not shown 

 in the figure. 



It is extremely strange that Mr. Bourne never saw these com- 

 missures in his dissociations; they are as strikingly visible as in 

 sections, and the clear spaces that separate them, even the shortest 

 ones, so clearly appear that " the student dissecting the leech for the 

 "first time" to whom Mr. Bourne is pleased to compare me, would 

 not have failed to see them. He writes however, in his critical 

 article: "I have never seen (nor apparently has Schultze) in teased 

 "preparation any thing like Mr. Bolsius' fig. 8 (3)." 



It is quite certain that he has seen some of them; but, like 

 Schultze, he has regarded the longest ones as free portions of the 

 whole organ. There is one of these commissures that seems to be 

 constantly much longer than the other ones, Ic, fig. 6 and 7 ; very prob- 

 ably Schultze and Bourne have taken it for what the latter calls 

 "recurrent lobe" or at least for some portion free from attachment 

 with the so-called main lobe. 



