532 JOSEPH STAFFORD, 



oviduct into the Laurer's canal no doubt indicates that their chief 

 purpose is correlated with the function of the latter organ. 



As to structure, the Laurer's canal appears to agree with the 

 other ducts of the genital apparatus. Epithelium nuclei are easily 

 seen, but the muscular layers outside of these are indistinct. It is, 

 except where distended with yolii cells, much narrower than the other 

 tubes. At its posterior end is a thick- walled bulb (Fig. 16, 23 LC), 

 lying a little to the right, between the end of the intestine and the 

 bladder-like swollen end of the right expulsion-canal. When the foot 

 and with it the genital glands are drawn forwards, this organ may 

 also be drawn more ventralwards and forwards, so that it then lies 

 under the end of the intestine 0,6 mm from the end of the body and 

 0,4 mm from the dorsal surface (in a sagittal section). In this case 

 it is on a level with ovary and testis, below the septum, and more 

 than one third the length of the animal from its posterior end. With 

 the dorsal surface, excretory vessels, or intestine it has no connection 

 being separated from them by parenchyma. 



As to histological structure, it assumes very different aspects 

 according to the ages of the animals under view. 1) In young animals, 

 before the sexual organs are perfected, it is simply the blind end of 

 the Laurer's canal — possessing the same structure and diameter. 

 2) In an animal where there are no primitive ova yet extruded into 

 the oviduct but where the vitelline glands are already ripe, I find the 

 following changes : Breadth of lumen 0,033 mm filled with yolk showing 

 nuclei, nucleoli and granules. The lumen is bounded by a thin mem- 

 brane exhibiting on its inner surface large nuclei with nucleoli. Out- 

 side of this membrane is a condensation of parenchyma cells for a 

 distance round , making up the whole structure to the diameter of 

 0,05 to 0,06 mm. The outer wall has decidedly no epithelial nature 

 and shows no radial arrangement from the lumen, either in cell bound- 

 aries or distribution of nuclei. It is as if small parenchyma cells 

 round the simple tubular end of the canal, while the latter became 

 distended with yolk, were stretched in a circular direction running 

 round the canal and likewise flattened in a radial direction to the 

 canal. These cells fall in an irregular position, accommodating them- 

 selves to the tensions of the contiguous parts, and shade towards their 

 periphery more or less completely into the encircling parenchyma cells. 

 Their nuclei, sli^^htly more numerous than in an equal surface of the 

 neighboring parenchyma, exhibit no appreciable difference in size, shape, 

 or contents from those outside of the condensation. The condensed 



