/ /.'. S ibin. 



lymphatic Bystem cai a and drawn. Thia was done by Clark. 



The specimen was then mi in serial sections and both blood capillaries 

 and lymphati reconstructed. Two reconstructions were made, 



one with the 1 nun. Zeiss objective, and the other with a 2 mm. Zeiss 



oil immersion lens. Both reconstructions Bhow that neither I>1 1 



capill r lymphatic capillaries can be reconstructed completely, 



ibtained with an oil immersion lens, 10th powers show 



capillaries in the form of rows of beads (figs. •">. u' and '•. Clark 26, 

 copied as 6gs. 513 and 51 1. Sabin L34 i. 



This te6t of Clark's is the best possible test, because it is a recon- 

 struction of exactly the Bame specimen from which the original draw- 

 ing was made. This point cannot be made in testing the method of in- 

 jection and that of reconstruction. For this tesl I (135) used, however, 

 symmetrical plexuses in the same embryo. An embryo pig ".'7 mm. 

 was chosen in which there was an almost complete injeetidn of the occip- 

 ital superficial lymphatics. Many of the sprouts on the margin had 

 ruptured. The injected plexus could of course be reconstructed, while a 

 istruction of the empty lymphatics on the opposite side showed the 

 entire plexus split up into isolated vessels i figs. 6, ] and 8, Sabin 135 i. 

 On the injected side there was just one lymphatic vessel which did not 

 recei jection mass, and there was an extravasation just at its 



This is readily explained by the fact that vessels are often con- 

 nected by very slender strands to the main plexus, as, for exampli , 



near the point of injection in li,u r . 1*. and a rupture might readily 

 ii- in such an area before the end of the vessel was reached. 



test of the two methods has now been made a third time by 

 Mrs. E. K. Clark (27) in her injection of the jugular lymphatic 

 rresponding to the one which Miller (97) has 

 reconstructed. The two results are shown in figs. 1 I and 1">. 



A i omparison of the injected jugular sac in a pig 18 nun., shown in 

 : . with reconstructions of the corresponding stages in the cat 

 (figs. 60 to 62, Huntington 55), also brings out the same point that, 

 wherever the injection iucih.nl can be applied, it demonstrates more 

 continuous lymphatics in an area than can be reconstructed, even as 

 isolated vessels. 



Undoubtedly an occasional hi 1 capillary or lymphatic capillary 



may from the main plexus and atrophy, but the apparentlj 



isolated vessels found in Berial sections along the course of grow- 

 ing lymphatics conned in life. Lymphatics do not grow h 



