46 



WILLIAM MORTON WHEELER, 



corpuscle. In Fetromyzon it happens that the glomeruli do not arise 

 as isolated structures but iu clusters, even in the anterior end of the 

 mesonephros, so that, as shown iu Fig. 65, there are usually two or 

 more funnels radiating from a mass, which is in reality made up of as 

 many glomeruli as there are funnels. Each funnel, however, retains 

 its own Bowman's capsule so that its cavity is com[)letely separated 

 from that of the neighboring funnels. Nor is this condition altered 

 essentially when the glomeruli unite to form the long compound 

 glomerulus of Vialleton's posterior mesonephric region. Here, too, 

 each tubule retains its own portion of the vascular trift, however 

 much the structure may become compounded, for this is the condition 

 of the tubule at the outset. Hence, what I have called isolated 

 glomeruli in my description are not really such, but small clusters of 

 glomeruli, separated from the large compound glomerulus which ex- 

 tends through the greater portion of the mesonephric fold in the 

 Ammocœtes. With the disappearance of the anterior portion of the 

 organ during the growth of the larva, only a single compound glome- 

 rulus persists in the adult as claimed by Meyer and Schneider. 



Concerning the vascular system in the kidneys and intestine of 

 the lamprey some confusion seems to prevail, and I am unfortunately 

 able to do little towards a solution of the difficulty. The subcardinal 

 sinus has been described by Rathke (1827), Johannes Müller (1845)^ 

 Berth (1867), Langerhans (1875) and Schneider (1879). Bert and 

 Schneider regard the sinus as a true blood vessel. In support of 

 this view the former cites the following experiment on Fetromyzon 

 marinus: "L'animal étant immobilisé par le curare, comme il va être 

 dit, je l'ouvre sur le flanc ; les grands sinus souscardinaux sont 

 flasques; graduellement ils se remplissent de sang; ce sang vient du 

 côté du coeur. Une ligature, placée sur la veine qui fait communiquer 

 le système rénal avec le système hépatique (arc hépato-néphritique 

 de Gratiolet) montre que le sang (l'expérience dure environ une 

 heure) va du rein au foie." With the majority of the authors above 

 cited and also in the well-known zootomies of Parker (1884) and 

 Vogt & Yung (1894) the subcardinal sinuses are regarded as lymph- 

 spaces. In 1894 Miss Agnes Claypole published some observations 

 on the subcardinal sinuses in P. marinus dorsatus. The structure 

 which she describes is obviously the same as the sinuses which I 

 have called the subcardinal together with the subaortic sinus. I quote 

 her description (1894, p. 132 — 133): "This sinus extends from near 

 the caudal end of the [alimentary] canal to the pericardium where it 



