130 
Planarian in the tanks of my laboratory. I found the contents 
had been obtained by the gardener from the pond in which the 
aquatic plants are grown in our botanic garden. I have no 
doubt it was the Vortex viridis of Max Scuuttze. I placed two 
of them in distilled water, and another in pond water carefully 
filtered. The fourth I kept for microscopic examination. The 
pair in distilled water lived for 24 days, the one in the filtered 
water was lost by accident after surviving for more than four 
weeks. From the remaining one I crushed out the green bodies, 
and submitted them to the action of re-agents. It is difficult 
to speak decidedly on one experiment with such minute sub- 3 
jects, but I am persuaded that starch is present in the cells, 
but further persuaded that they do not resemble any form of 
algae I have ever seen, either amongst the hundreds of speci- 
mens of this or any other pond water examined by me, or in 
any description of algae seen by others. 
I shall look out with great care for other specimens of 
this Planarian, and submit to you any further observations that 
may be made by us. It will be manifest that much further 
observation is needed before we can come to the conclusion 
that this form of symbiosis is an established fact. 
