21 



containing tube, could be examined as readily in situ as when extract- 

 ed from the joints. In either case they appeared to consist of an en- 

 veloping membrane, which was probably formed by the aggregation 

 of the green granules of the plant, assisted by the condensation of the 

 mucous fluid of the interior ; and thus forming an investing capsule, 

 which, when torn open, was found to be filled by the green granules 

 of the plant mixed with mucous fluid, (PI. ii. fig. 11). The investing 

 capsule was very thin, and presented no other traces of structure than 

 that which would arise from the formation of a membrane by the ag- 

 gregation of granular matter. 



In those joints in which the brown bodies had been formed, the 

 green matter of the plant had in most cases entirely disappeared. In 

 others, where they appeared to be in process of formation, they were 

 observed to be mixed with the green matter ; and in other parts again 

 they had not yet undergone the change from green to brown, but 

 showed themselves in the form of irregular masses of green matter ap- 

 proaching the spherical form. 



It appears then that this remarkable change had taken place within 

 a week after the circulation had been observed to be going on vigor- 

 ously in the plant. And the nature of the change appears to be this. 

 The green granules which line the internal surface of the living joints 

 desert the parietes, and, together with the green circulating granules 

 of the interior collect together in irregular masses in the centre of the 

 tube, which then resolve themselves into irregular spheres, still retain 

 ing the granular outline, indicative of their formation by aggregation, 

 but which they afterwards lose on assuming a more perfect spherical 

 form, and become bounded by an investing capsule, which turns of a 

 rich brown color, while the contained granules retain their original 

 green. 



It is difficult to imagine what purpose is intended to be answered 

 by such a change taking place, after all circulation and other evi- 

 dences of life in the plant have ceased. Yet the idea of such a change 

 being the result of a merely fortuitous arrangement of the component 

 particles of the plant attendant on decomposition, is negatived by the 

 circumstance of the remarkable uniformity and symmetry of the re- 

 sulting globules, which appear to possess the most definite characters, 

 differing from each other only in size. Nor is the change by any 

 means uniform for the whole plant; for in some parts two of the joints 

 were observed to be in the green state, while the joint situated between 

 them was free from green matter and contained the brown bodies : but 

 this might have resulted from the circulation ceasing earlier in the 



