ON THE DEVELOPMENT OF TUBULIPORA. 117 



granules in active movement. These become larger, and on 

 coming to rest form the granules seen even in sections in the 

 interior of the vesicles. One fresh vesicle always gives rise to 

 one precipitated vesicle. 



The amount of the precipitate produced by various reagents 

 is not identical. Ammonia gives rise to a specially copious 

 precipitation, the vesicles now looking very dark, and some- 

 times dissolving after a prolonged action of the ammonia. 

 The addition of strong potash now broke up the precipitated 

 granules^ with some indication of solution, during which a 

 purplish colour appeared. Osmic acid similarly gives rise to 

 a very dark-coloured precipitate ; but when added to vesicles 

 which have recently been precipitated by corrosive sublimate, 

 it merely slightly darkens their granules. 



In most of the above-described experiments no trace was 

 seen in the fresh material of precipitated vesicles, but these 

 were observed in one or two specimens. It is, I think, 

 probable that precipitation of the granules takes place during 

 life in old vesicles ; but it seems clear that the young stages of 

 these bodies consist merely of a homogeneous fluid. 



While the above reagents produced precipitation of the 

 vesicles, others dissolved them completely. 90 per cent, 

 alcohol at once dissolves them without precipitation, and the 

 same effect is produced by 30 per cent, alcohol, which does 

 not affect the yellow granules above described in other parts of 

 the tentacles. The vesicle is indicated as an empty space in 

 the tentacle after the addition of alcohol. Nitric acid dis- 

 solves the fresh vesicles, giving rise to a red-brown mass. 

 Dilute acetic acid has no effect. 



When the vesicles have been precipitated^ their behaviour 

 towards reagents is entirely different from that of fresh 

 vesicles. Alcohol, even weak alcohol, readily dissolves the 

 latter, but it has no effect on vesicles which have been pre- 

 cipitated with corrosive sublimate, as is obvious enough from 

 the fact that they are seen in sections. 



The vesicles of some sublimate-material which had been 

 kept in 70 per cent, spirit for seven or eight months were ex- 



