120 FROFESSOR E. RAY LANKESTER. 
disintegration of the animals taken in is performed by juices 
secreted by the endoderm cells; but the final digestion seems to 
take place in the actual protoplasm of the cells, into which the 
food particles are taken in the solid form. He does not suggest 
how the digested material is distributed to the other cells of the 
Hydra. 
asi, we have a brief réswme from Metschnikoff in the 
‘Zoolog. Anzeiger,’ No. 56, May, 1880, of a series of observa- 
tions on the subject of intra-cellular digestion, carried on by him 
in the spring at the Zoological Station at Naples. 
Metschnikoff made use of carmine powder, which he observed 
to penetrate the endoderm cells in many Hydroid polyps and 
Hydromedusee (Plumularia, Tubularia, Eucope, Oceania, Tiara, 
Praya, Forskalia, Hippopodius, Pelagia, Beroe among Cteno- 
phora and Sagartia and Aiptasia among Anthozoa.) In the 
Trachymedusee Liriope, Carmarina, Cunina, Metschnikoff failed 
to establish the occurrence of intra-cellular digestion. It will 
be observed that the method employed by Metschnikoff is not 
altogether a conclusive one. The majority of forms studied by 
him, like the Hydra studied by Parker, are opaque, and, conse- 
quently, it was not possible to watch the process of ingestion 
during life. In Praya, however, Metschnikoff studied a trans- 
parent form, and was able to observe the throwing out of 
pseudopodia by the endoderm cells, and their fusion into a 
plasmodium. ven here, however, it seems that there is still 
room for doubt as to whether the pseudopodia are really active 
in digestion, for Metschnikoff only speaks of their penetration 
by carmine particies. It is exceedingly probable that when his 
observations appear at greater length, we shall find that they 
include the fact of inception of natural food materials, such as 
Alge, disintegrated Entomostraca, &c. The mere penetration of 
minute particles like those of powdered carmine into amceboid 
cells would not in itself indicate a natural process of intra-cel- 
lular digestion. Such a penetration of carmine particles into the 
amceboid corpuscles of vertebrate blood is well known, and does 
not in that case lead to the inference of normally occurring 
intra-cellular digestion. 
On this account I think some importance attaches to the 
observations which I made last summer on the intra-cellular 
digestion of Limnocodium, the fresh-water Medusa discovered 
in the lily-house of the Botanical Gardens, Regent’s Park, 
London. I was able, in this animal, on avcount of its exceeding 
transparency, to study the endoderm cells during life, and to 
establish the fact of the inception of natural food materials 
by those cells. 
I have since made a careful study of the endoderm of various 
