554 REVIEW. 



drain-pipe cells other than the central lumen. These may be 

 vacuoles (M. Bolsius figures what he calls vacuoles in his 1, 

 fig. 23) ; but I think that it is more likely that they are 

 ramifications of the central lumen in the cell substance, just 

 as the lumen in, for instance, a cell of the main lobe consists 

 of a branching tube running into the neighbouring cells with 

 ramifications in the substance of the cell itself. 



I propose to speak of the course of the duct and the 

 arrangement of the lobes in one or two particular spots as a 

 test of M. Bolsius^s views. 



It can very easily be proved, for instance, by dissection that 

 the testis lobe is distinct from the apical lobe, and that it 

 joins the anterior limb of the main lobe at the point where 

 the latter is joined by the vesical duct; in other words, that 

 the vesical duct, coming from the vesical, first plunges into a 

 mass of glandular cells, near what most of my readers will 

 doubtless allow me to call the '' funnel" end of the organ. A 

 study of a few nephridia mounted fresh under the microscope, 

 or stained and mounted whole in Canada balsam, must, I 

 think, convince even M. Bolsius that this is so, and that his 

 diagrams (1, fig. 1 ; and 4, fig. 17) are therefore fundamentally 

 wrong. If he is really unable, as he says, to make satisfactory 

 preparations of this kind he should find it perfectly easy to 

 trace in a series of sections the testis lobe passing round the 

 edge of the apical lobe to the point where its cells join those 

 of the anterior limb of the brain lobe, and to trace the vesical 

 duct from the vesicle until it plunges into a mass of glandular 

 cells at this point ; into the mass of cells, in fact, which consti- 

 tute the anterior limb of the main lobe. If the nephridium 

 is built upon the plan suggested by M. Bolsius the term used 

 by him, *' Textremite de I'organe," obviously refers to the 

 "funnel" end of the testis lobe, since this is the only region 

 where the cells with ductules do not envelop a duct. One 

 mav speak of the course of the organ from this point to the 

 vesicle (a to 6 to c to (/ to e in 4, fig. 17). According to M. 

 Bolsius, the collecting canal always advances along this course 

 towards the vesicle. Now once it is established — and there is, 



