1906.] " REXAL-POilTAL SYSTEM." 899 



The coccygeo-inesenteric of Apteryx also (and pei'haps tliat of 

 other birds) is, in the alxsence of a renal meshwork, similarly to be 

 interpreted — the blood, owing to the absence of a powerful tail 

 and the shape and position of the trunk relatively to the ground, 

 finding the ventral clmnnel as easy of ])assage as tlie dorsal. 



[JSToTE. — I am indebted to Mr, F. E. Beddiird for kindly 

 drawing my attention to several facts observed by him in ceitain 

 Lacertilia and Ophidia which at first sight suggest that the 

 blood-flow in the " renal- portal " and certain abdominal veins is 

 <lirected posieriorly and not anteiioi-ly, as is genei'aJly assumed. 

 To settle this point at least for the Frog I performed the following 

 experiment — more for my own satisfaction than because I have 

 any reason to believe that it has not Ijeen pei'foimed before, as 

 doubtless it has been. 1 jDithed a frog, destroying both the brain 

 and spinal cord and then removed as much as possible of the body- 

 wall both ventrally (leaving of course a strip on each side of the 

 anterior abdominal) and dorsally and of the viscera without in- 

 juring any large vessel. I then laid the frog, ventral side upwards 

 Mild somewhat to one side, on a microscope st;ige powei-fully 

 illuminated from below, and with fine forceps gently pulled into 

 the line of reflected light first the anterior abdominal and then 

 the post-renal. The heart still beating vigorously, the blood could 

 easily be observed, even under the low power, rushing anteriorly 

 in both the post-renal and the anterior abdominal veins. I re- 

 peated the experiment several times on the frog and once on the 

 newt, always with the same resiilt. But the particular modes of 

 disposition of the posterior veins observed by Mr. Beddard diflfer 

 from the condition found in the frog, newt, and most amphibia 

 and reptiles in that the post-renals, instead of wholly emptying 

 themselves into the kidney-substance, are continued anteriorly 

 for some distance and apparently terminate by small branches 

 (resembling factors) in the parietal muscles (see Beddard, " Con- 

 tributions to the Anatomy of the Lacertilia," P. Z. S. 1904, 

 vol. ii. p. 15, text-fig. 4; also P. Z. S. 1906, p. 38, text-fig. 10, 

 and P. Z. S. 1906, p. 511, text-fig. 90). In Fygojms le2ndopus, 

 to take a conspicuous example from the first of the papers just 

 referred to, not only the left post-renal terminates in this manner 

 (the right terminating as in the frog), but also the two lateral 

 abdominals — two veins arising from the femorals and running 

 anteriorly and laterally in the body-wall for a short distance in 

 front of the kidneys and terminating in what ajjpear to be factors. 

 ISTow I fully admit the possibility (though not the probability) 

 of the blood flowing posteriorly in the lateial abdominals 

 and in the anterior prolongation of the left post-renal (this latter 

 in such a case being comparable to a dorso-lumbar, the blood, 

 flowing posteriorly and meeting with the anterior blood-flow in 

 the post-renal proper, being forced into the afierent kidne}^ veins 

 by the resulting pressure — see Shore on an abnormal anterior 

 prolongation of the "renal-portal" in the Frog, Jour. Anat. 



