OBSERVATIONS ON THE GENUS PYTHIUM. 493 



protoplasmic contents of the oogonium, part being left 

 between it and the walls. 



Shortly after the stage just described — the period of excite- 

 ment, so to speak — culminated in the passage of the contents of 

 the antheridium-tube towards the oosphere, and by 10.55 (cf. 

 fig. 10, d) this process was fairly commenced. Close and careful 

 observation of the contents of the antheridium and its "fer- 

 tilising tube" convinced me that the large, brilliant granules 

 were gradually being carried through the tube into the 

 oosphere by means of a slow, more or less continuous, current 

 of protoplasm. 



There is not the slightest doubt of the accuracy of this ob- 

 servation. A particular granule just about to eijter the tube 

 at 10.55 (fig. 10, d) was observed to pass slowly into the tube, 

 and disappear at the other end (fig. 10, e) in less than five 

 minutes. The motion was not rapid, but consisted of a gradual, 

 steady streaming, as a comparison of figs. 10, d to J", shows. In 

 some cases the granules appeared to melt away in the tube. 

 Meanwhile, the granules in the antheridium were slowly 

 accumulating at its upper part, each to be carried down the 

 tube in turn. At 11.10 (fig. 10, y) two distinct vacuoles, sepa- 

 rated by streaming protoplasm, appeared in the antheridium; 

 and by 11.30, three or four others had been formed. At this 

 time, also, nearly all the remaining bright granules were 

 aggregated at the entrance of the tube (fig. 10, g), and a com- 

 paratively rapid passage of these through the tube occurred 

 during the next five minutes (cf. fig. 10, g and h). The slow 

 revolving motion of the oosphere was still taking place; but the 

 tube was plunged further into the substance of the oosphere 

 at 11.30, for instance, than at 11.10, as shown in figs. 10, g 

 and y respectively. 



At 11.45 the last three of the large granules began to pass 

 over (fig. 10, i) in the final flow of protoplasm, and the vacuoles 

 now became very large. The remaining hyaline protoplasm 

 was still, however, slowly streaming towards the mouth of the 

 fertilising tube, and much of it passed through during the next 

 three quarters of an hour, the quantity left in the antheri- 



