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nature of the chlorophylloid colouring substance of Spongilla, 
in which he has determined its compound characters as agreeing 
in this respect with the chlorophyll of plants. In a planarian 
worm common on the sea-shore, Geppxs found that on exposure 
to light from 45 to 50 per cent. of oxygen was given off. The 
Lecturer next proceeded to relate certain experiments of his 
own on the nature of the green colouring matter of Englena 
viridis. At a lecture at Stroud he mentioned his desire to 
procure pure gatherings of Englena. This bore fruit, and Mr 
Houtanp sent a gathering which proved to consist entirely of 
Englena. These were treated by Mr Hoxuanp as if for the 
chlorophyll of plants, when it was found that the re-action, 
both chemical and spectroscopic, were those of chlorophyll. 
Further, he found that the colouring matter was a compound, 
as in the Spongilla examined by Sorsy. These experiments 
were repeated with the specimens sent, which were further 
submitted to the action of sunlight, when the giving off of 
oxygen was detected; but a most careful examination failed 
to detect the presence of starch. The chlorophyll in Englena 
is diffused throughout the entire animal, and is not in granules, 
as in Spongilla and Hydra. The Professor next referred to 
the “yellow cells” of Huxury, in Radiolarians, thought by 
Haxrcxet to be secreting cells, although he found starch in 
them. In 1871 Crenxowsx1 found that they survived after the 
death of the animal, and thought them parasitic. In 1881 
Branpt of Berlin regarded them as independent organisms, 
and gave them the names of Zoochlorella and Zoanthella, of the 
nature of alge, and parasitic. Similarly he considered the 
green cells of Hydra and Spongilla to be alge. Therefore he 
concluded that the chlorophyll does not pertain to the animal, 
but to the parasitic alge. In 1882 Geppxs confirmed Branpt 
to a certain extent. He found the walls of the yellow cells in 
Radiolaria to be true plant cellulose, and advocated the theory of 
mutual interdependence, to which has been applied the term 
“Symbiosis.” In the spring of this year Professor Harker 
found in his tank a Rhabdocell Planarian, with green chlo- 
rophyll, not resembling any known algal; it lived in distilled 
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