"The tentacles, alimentary canal, and nervous system break down, and the tentacles cease to be capable of being protruded. The degenerating organs become compacted into a rounded mass, known from its colour as the 'brown body.' This structure may readily be seen in a large proportion of the zooecia of transparent species. In active parts of the colony of the body-wall next develops an internal bud-like structure, which rapidly acquires the form of a new polypide. This takes the place originally occupied by the old polypide, while the latter may either remain in the zooecium in the permanent form of a 'brown body,' or pass to the exterior. In _Flustra_ the young polypide-bud becomes connected with the 'brown body' by a funiculus. The apex of the blind pouch or 'cæcum' of the young stomach is guided by this strand to the 'brown body,' which it partially surrounds. The 'brown body' then breaks up, and its fragments pass into the cavity of the stomach, from which they reach the exterior by means of the anus." Brown bodies are rarely if ever found in the phylactolæmata, in which the life of the colony is always short; but they are not uncommon in _Hislopia_ and _Victorella_, although in the case of the former they may easily escape notice on account of the fact that they are much paler in colour than is usually the case. When they are found in a ctenostome the collar-like membrane characteristic of the suborder is extruded from the orifice (which then disappears) and remains as a conspicuous external addition to the zooecium, the ectocyst of which, at any rate in _Bowerbankia_ and _Victorella_, sometimes becomes thickened and dark in colour. It is noteworthy that the colouring matter of the brown bodies is practically the only colouring matter found in the polypides of most polyzoa. Young polypides are practically colourless in almost all cases. REPRODUCTION: BUDDING. Polyzoa reproduce their species in three ways--(i) by means of eggs, (ii) by budding, and (iii) by means of bodies developed asexually and capable of lying dormant in unfavourable conditions without losing their vitality. Most, if not all species are hermaphrodite, eggs and spermatozoa being produced either simultaneously or in succession by each individual, or by certain individuals in each zoarium. The reproductive organs are borne on the inner surface of the endocyst, as a rule in a definite position, and often in connection with the funiculus or funiculi. It is doubtful to what extent eggs are habitually fertilized by spermatozoa of the individual that has borne them, but in some cases this is practically impossible and spermatozoa from other individuals must be introduced into the zooecium.