INTRACELLULAR DIGESTION OP THE INVERTEBRATES. 93 



granules are digested in order to provide material for the build- 

 ing up of new polyps. The so-called neraatocalyces must 

 therefore be classed among organs whose chief function is 

 prophylactic ; they eat up necrotic parts of the colony, and 

 also continually explore the organs in their vicinity, in order to 

 render harmless by devouring them any injurious bodies which 

 may be present. Any offensive or defensive function seems to 

 be purely secondary; at least the larger of my species had no 

 nematocysts in its " nematocalyces.^' 



It seems probable that the peculiar organs described by 

 Weissmann^ in Endendrium racemosum, and the tendrils 

 observed by Fraipont ^ in Campanularia angulata, serve 

 the same function as that of the nematocalyces of Plumularia. 



The Actinias give us another case of the ingestion of solid 

 food by the ectoderm. Three years ago, in my work on the 

 development of Actinia mesembryanthemum, I showed 

 that the tentacles of this creature habitually take up a 

 large number of carmine granules. During the past year I 

 have studied the viviparous edible Actinia of Pantano (which is 

 identical with the new Bunodes sabelloides of Dr. Andres), 

 and I found that the larvae of this species also contained in 

 their ectoderm a large quantity of foreign matter. The 

 younger the larva, the more abundant were the extraneous 

 granules. One can often find Gastrulse, whose bodies are 

 asymmetrically swollen, and dirty looking. Examination 

 shows that this dirtiness is not due to particles adhering to the 

 outside, but that it arises from the presence in the ectoderm 

 cells of foreign bodies, sometimes black, irregular or angular, 

 sometimes rounded and fatty or albuminoid in character. The 

 periphery of the ectoderm (which seems from examination 

 of the living larva to have all its cells fused into a common 

 homogeneous ectoplasmic mass) is free from granules, all the 

 ingested matter being in the deeper parts of the protoplasm, 

 either just in front of the nucleus, or behind it. The particles 



' • Mittheil. aus d. zool. Stat, zu Neapel,' iii, 1882, p. 1. 

 ' ' Recberches sur I'organ. histol. et le develop, de la Campan angul,' ' Arch. 

 Zool. Exp.,' viii, 1879, 1880, p. 442. 



