of the. Organs o/'Pilularia j,duhulitera. 497 



Fig. 32. Anotlier view of a union of sporules in theii- first stage. 



Fig. 33. A union in its second stage; the motlier-cell is now visiijle : — magni- 

 fied 150 times. 



Fig. 34. An abortive sporule in the third stage: — magnified 120 times. 



Fig. 35. An abortive sporule after it has acquired its outer coat, bnt before 

 the coat has become thick enough to obscure the lines on the spo- 

 rule. 



Fig. 36. An abortive sporule in its final shape. 



Fig. 37. Fertile sporule in the third stage. Three of the sporules are rup- 

 tured ; the other is enlarged: — magnified rather more than 100 

 times. 



Fig. 38. A union of sporules from a fertile theca, in which all four of the spo- 

 rules are ruptured. 



Fig. 39. Is the same as fig. 37, but more advanced ; the sporule is consider- 

 ably eidarged and of a pyriform shape; the mother-cell is consider- 

 ably dilated. 



Fig. 40. A more advanced sporule. There is a considerable deposition of 

 matter around tlie upper part of the sporule, and also a beginning 

 at the larger extremity. The three ruptured sporules have disap- 

 peared : — magnified 54 times. 



Fig. 41. A still more mature sporule. 



Fig. 42. A ripe sporule in its theca removed from the involucrum. The 

 action of the water in which it was examined on the gelatinous 

 covering, and its being removed from the pressure of the other 

 thecfe, have caused the theca to swell and assume a roundish figure, 

 a. One of the four visible unions of ruptured sporules. 



