4O HAROLD SELLERS COLTON. 



these things our attention is particularly called to the relative 

 fewness of flagella and nuclei in the terminal portions of the tu- 

 bules. Figs. 4-13 show flagella while Figs. 14 and 15 show nuclei. 

 Although it is not possible to distinguish cell boundaries either in 

 the preserved material or in the living tissue, yet the fewness 

 of thr nuclei might suggest the possibility that the cells composing 

 this part of the gland have intracellular lumens. Again the ter- 

 minal ends of these tubes exhibit two different types. We may 

 ha\ e those unsegmented with a very small lumen, 2-6 p (Figs. 

 8-12, 14 and 15), or we may have segmented tubes with a much 

 larger lumen, 4-10 fj.. In the first type of tube our attention is 

 at once attracted to the terminal end of the tube. In most cases 

 there seems to be a very thin place in the walls of the tubes. 

 This thin place may be formed in three ways: (i) by the lumen 

 of the tube approaching the exterior (Figs. 8, 14, 15), (2) by a 

 cup-like depression in the end of the tube (Figs. 9-12, 15), (3) 

 by a vacuole in the wall of the tube which does not communicate 

 either with the exterior or the interior. To these three cases 

 there is a fourth effect that the writer has observed. He thought 

 that he could see tubes less than a micron in diameter that formed 

 a direct communication between the interior of the tube and the 

 blood space. The structures found at the end of the rectal 

 tubules are so small that what we may interpret as a duct may be 

 nothing more than a division bet ween two cells or a nucleus 

 both of which look clearer in preserved material and in the living 

 tissue than the cytoplasm of the cell. The cup-like depression 

 at the end of the tube suggests the organ of Boveri as found in 

 Amphioxiis or perhaps a nephridial funnel. Tin- writer has 

 searched tin- neighborhood about the ends of the lubes to see if 

 he could find solenocytes as described by ('.oodrich ('09) in 

 Anif>liio\iis but without re>ult. Again he has watched particles 

 in the blood in the neighborhood of the possible opening, yet in 

 no case ha-; he been able to obser\ e Mich a panicle enter the tube. 

 In this connection the experiment of KuptTer ('72) is interesting. 

 He sa\ - (p. 381): "Mir ist es audi bei Asiitiin rnnina gelungen, 

 dieses Sy-tem wenigsten- partiell vom Herzen ails zu injiciren. 

 Die Injectionsmasse war in melm-tv der blinden Anhange einge- 

 drungen. Solche blinde kolliige Anhange sind auch niehts Neues 



