48 BR. KLEIN. 



a curve from right to left, Avhile further inwards the two cells 

 were propelled in a circle from left to right. 



But there is still another variety of similar cells, con- 

 taining vacuoles, which may be observed. These are dis- 

 tinguished from the former by this peculiarity, that the 

 wall which edges the vacuole possesses at individual spots 

 smaller and larger knobs, Avhich consist of a granular proto- 

 plasm and contain an oblong nucleus. These knobs them- 

 selves, again, have the appearance of being, in some places, in 

 the act of division ; at least, one finds them occupied by a 

 groove, involving them more or less deeply. Or, on the 

 other hand, the protoplasmatic wall exhibits, instead of these 

 cells, oblong nuclei at regular intervals, corresponding with 

 each of which the wall is thicker and projects into the vacuole, 

 so that in profile an appearance is produced as if the vacuole 

 were bordered by a layer of thin spindle-shaped cjIIs fused at 

 their extremities. Externally there appears to be here also 

 a clear hyaline membrane. On vacuole cells so completely 

 formed Ave can further determine another fact, viz. that 

 the border limiting the vacuole does not support cilia in 

 its whole extent. The more distinctly the vacuole appears 

 lined with separate cells — that is, the more the wall has been 

 differentiated into separate cells — the more seldom do we find 

 cilia everywhere. We find only here and there separate 

 cilia, or a bunch consisting of a few cilia. The cilia are also 

 thicker, and appear to be shorter as well. 



On the other hand I must, however, mention that I once 

 found vacuoles coming up to 0'35 mm. in diameter, whose 

 border was completely covered with cilia. These occurred 

 on the mesogastrium of a female Rana temporaria, which 

 presented no striking abnormality beyond very abundant 

 vacuoles of the most various size, lined with cilia. 



It was here, too, that I was able to discover among those 

 well-known lymph sinuses which accompany the great blood- 

 vessels of the mesentery of the frog (compare Strieker's ' Hand- 

 book,' chapter xxvii) one whose endothelium was also 

 everywhere ciliated. This sinus, spherical in shape, 

 0'3 mm. in diameter, sharply bordered, and containing no 

 formed constituents I could see with the greatest certainty 

 communicating with the free surface by means of a stomatous 

 opening not larger than a colourless blood-corpuscle. The 

 stoma was lined with ciliated, yet cubical, cells. In the 

 sinus the ciliary movement went on everywhere with great 

 liveliness. 



In individual specimens I find, like Remak, large vesicles, 

 in which foreign bodies of the most various kinds are con- 



