42 REPORT ON THE PENNATULIDA. 



The structure of the shoi-t mesenterial filaments is, as shown in Figs. 

 4 and y, the same as in Funiculina, each consisting of a connective 

 tissue lamella clothed on each side by a thick layer of special glandular 

 and ciliated endodermal cells. Concerning the function of these 

 filaments we have been able to make some observations whic'.i tend to 

 strongly confirm Dr. Krukeuberg's conclusions* that they are really 

 digestive organs. 



In a number of the polypes we have observed solid bodies imbedded 

 either partially or completely in the mesenterial filaments ; examples of 

 this are shown in the third section in Fig. 5, to. These bodies are 

 cleai-ly of a foreign nature ; they are also evidently organised, and 

 appear to be undergoing decomposition. From the observations of Dr. 

 Krukenberg on the digestive properties of these mesenterial filaments 

 in Sea-anemones, there can be no doubt that these foreign bodies are 

 organisms or portions of organisms which have been swallowed 

 as food and are undergoing digestion. In this case it is of 

 great interest to notice the veiy marked power possessed by the fila- 

 ments of wrapping themselves around the food particle, so as to attack 

 it, as it were, from all sides at once. The importance of this operation 

 is seen at once from Dr. Krukenberg's account of the act of digestion 

 as being a surface action, only occurring where there is actual contact 

 between the filament and the food particle, and not effected by means 

 of a fluid secretion poured out over the food. 



It is also important to notice that the endodermal cells of the 

 mesenterial filaments must in order to effect this enveloping of the 

 food, manifest active changes of form — i.e., must be amoeboid, and the 

 fact that those endoderm cells which are specially concerned in 

 digestion are amoeboid has now been established in a considerable 

 number of C(denteratn. 



In the case of one of the polypes of which we have prepared 

 sections — the third section fi-om the top in Fig. o — an additional point 

 of interest has presented itself. Lodged within the polype with its 

 head just at the level of the bottom of the stomach, and its body lying 

 imbedded among the mesenterial filaments, is an Entomostracon, 

 apparently one of those parasitic or semi-parasitic Copcpoda in which 

 the jaws are retained in a well-developed condition, but the other 

 appendages are rudimentary. The ovaries of this Copepod are in a 

 condition of great activity, containing very numerous ova in various 

 stages of development. Many of the ripe ova have left the parent and 

 are either lying freely in the body-cavity of the polype or else are 

 embedded in the mesenterial filaments in the same manner as are the 

 food particles described above. An instance of this is shown in the 



* Vide supra, v. 1". 



\ For a summary of receut observations on the amoeboid condition of the 

 endoderm in Ccelenterata and other forms, and for important observations on 

 the process of di^'estion in the fresli-water Medusa Limnocodium, vide Lanliester 

 "On the Intracellular Digestion of Limnocodium," Quartcidy Journal of 

 Microscopic Scioiioe, -January, 1S81. 



