344 CRESSWELL SHEARER. 



at the sam6 poitit. The yolk-granules then rapidly poured 

 through the opening into the sea-water, and carried the 

 amphiiister with them. It held together as a semi-solid body, 

 and could be seen turning over and over as it was pushed 

 along by the granules. Once in the water outside the body 

 the granules tended to disjaerse, while the amphiaster remained 

 with its immediate surrounding granules, apparently a solid 

 body. It remained like this for several minutes until it finally 

 dissolved and disintegrated. I have tried to represent this 

 taking place in fig. 8. The asters go first, while the central 

 spindle still remains intact. This seems to show that the 

 substance ol the spindle is of firmer texture than that ot' the 

 asters and centrosphere ; and this is borne out, as I have 

 mentioned, by the actual appearance of the archoplasmic 

 substance of the asters as compared with the sharp, definite 

 structure of the spindle. The yolk-granules adhere and 

 seem almost a part of the archoplasmic substance of both 

 asters and spindle, the amphiaster really appearing as a mass 

 of brown yolk-granules held together by the thread-like 

 archoplasmic substance. As the spindle begins to dissolve 

 the yolk-granules can be seen being liberated from the trans- 

 parent substance of the archoplasm and moving away in the 

 sea-water. In fact the whole process of the dissolution of 

 the amphiaster, as seen under an oil-immersion lens, is similar 

 to that of some gelatinous substance slowly dissolved by the 

 action of sea-water. That the spindle has some considerable 

 rigidity is borne out by the fact that it keeps its shape, and 

 can be seen rolling over and over as it is drawn along in the 

 sea-water. It shows no tendency at first to flatten under the 

 pressure of the cover-glass. This is always considerable, 

 although its corners ai-e supported as much as possible by wax 

 feet, as the capillary attraction invariably draws the cover- 

 glass down somewhat in the middle. It is not till the spindle 

 has begun to dissolve that this rigidity is lost, when it under- 

 goes flattening. It at the same time becomes more trans- 

 parent, the archoplasmic threads appearing as if actually 

 undergoing dissolution by the sea-water, leaving the dark 



