CORNEOUS FILAMENTS OF PERITONEUM OF FROG. 47 



excentrically. In the cavity just mentioned we remark a 

 lively movement; as if on the wall of the hollow a numher of 

 small! granules were in rapid motion in a certain direction. 

 If we inspect tliis more closely, we become aware that the 

 appearance is due to nothing else than the uncommonly 

 rapid movement of fine short cilia. But this is not all we 

 can discover on our preparation. We find other spherical ele- 

 ments in the tissue which are rather larger than (about twice 

 the size of) those just described. In them also we may perceive 

 a cavity, just as much lai-ger, in which the cilia projecting 

 into it may be seen even with greater ease. Further, we 

 find globular structures, about four times as large, enclosing 

 a vacuole, which is not inferior in size to the lumen of a large 

 microscopic blood-vessel. In the smaller ones the vacuole 

 is bordered by a thin layer of a granular protoplasm, in 

 which we may observe at one spot a nucleus undergoing 

 division. Towards the outside this protoplasm appears 

 boi'dered by a delicate hyaline membrane. The cilia which 

 project into the vacuole are seen with extraordinary clearness ; 

 their motion is just as rapid as that in the superficial endo- 

 thelial cells. 



This movement of the cilia I have found quite- as lively 

 after the specimen had been mounted for four hours in 

 serum. 



In the interior of the vacuoles we see also one or two young 

 cells, with one or more nuclei, as well as several smaller and 

 larger granules, kept in rotation by tlie ciliary motion. The 

 most interesting appearance I have seen in this way was the 

 following. On one of the above-mentioned hair-shaped 

 structures, found on the border of the preparation, there hung 

 freely from the surface a knot covered with what might 

 almost be called cubical endothelium, furnished with cilia 

 moving in a lively manner. In the middle of the knot lay 

 a large cell with a large vacuole. Within the vacuole 

 there was also lively ciliary motion. From a vessel, which 

 was to be found to the right of this, there were welled out 

 blood corpuscles in numbers (from the pressure of the covering 

 glass). These had scarcely escaped when they were swiftly 

 chased away towards the left, in a semicircle, by the move- 

 ment of the ciliated endothelium of the knot. In the vacuole 

 of the cell which lay in the knot, there were two somewhat 

 differently sized spherical cells; these were chased round in 

 a direction from left to right. If now I adjusted the prepa- 

 ration, so that I could see at once both the border of the knot 

 and the vacuole, I was witness of a most extraordinary 

 spectacle — in the one place, the blood-corpuscles driven in 



