452 



Mr. P. Geddes. Observations on the [Mar. 27, 



nauseous and uneatable — holds good here. So strong and disagreeable 

 is the odour, to which the taste doubtless corresponds, that this alone 

 might be relied upon as a protection against the least fastidious of 

 fishes or Crustaceans. 



The chemical examination of the animal yields results of interest. 

 Treated with alcohol, a yellow substance, contained in small elongated 

 vesicles, aggregations of which are dotted over the integument, dis- 

 solves out very rapidly, yielding a golden solution without definite 

 spectrum. This has of course nothing to do with xanthophyll. Con- 

 tinued treatment with alcohol dissolves out the chlorophyll, of which 

 the magnificent green solution is tolerably permanent. As former 

 observers have shown, it has a red fluorescence, and gives a spectrum 

 closely resembling that of vegetable chlorophyll. 



Knowing that these animals decompose carbonic acid, and evolve 

 oxygen, one naturally enquires whether they do not still more com- 

 pletely resemble green plants in fixing the carbon in the same way. 

 To answer this question, the^residue of the Planarians, coagulated and 

 decolorised by repeated treatment with alcohol and ether, was boiled 

 with water, and filtered off. The clear solution gave with iodiue solu- 

 tion a deep blue coloration, which disappeared on heating, and reap- 

 peared on cooling, indicating the presence in quantity of ordinary 

 vegetable starch. 



To separate and purify this starch on a large scale, some hundred 

 grammes of Planarians were repeatedly boiled in water. The solution 

 (which had an intensely alkaline reaction) was treated with four or 

 five times its bulk of strong alcohol, and allowed to stand for some 

 days. The flocculent precipitate was collected, decolorised with 

 ether, and washed with cold water. A great part of it dissolved, 

 leaving the starch behind, and the filtered solution gave with iodine 

 the red-brown coloration characteristic of dextrine. To ascertain 

 whether this dextrine was naturally present, or had merely been pro- 

 duced at the expense of the starch by boiling in alkaline solution, fresh 

 animals were treated with cold water, but the solution contained no 

 dextrine. Treatment of a fresh microscopic preparation with iodine 

 showed the presence of glycogen, in the colourless amoeboid cells of 

 the mesoderm, but there is no chemical means of separating glycogen 

 from starch. Probably the best way of obtaining pure starch from 

 these animals would be by imitating the mechanical process of the 

 potato mill. 



The intense alkalinity of the animals is very striking. Even in the 

 fresh state, but still more when dried in the warm chamber, they give 

 off vapours with an odour resembling that of trimethylamine, and in 

 such abundance as to cause neighbouring solutions to yield the reac- 

 tions of an alkaloid. A quantity of animals was distilled, and the 

 alkaline fumes received in dilute hydrochloric acid. The resultant salt 



