NINTH LECTURE. 



PROTOPLASMIC CONTRACTILITY AND 

 PHOSPHORESCENCE. 



S. WATASfi. 

 I. 



IT is now generally admitted that the emission of light from 

 an animal organism is due to oxidation of a certain substance 

 produced by the metabolism of the cell. This is easily proved 

 in the case of a glowworm or a firefly, where the photogenic 

 tissue can be separated from the organism artificially and sub- 

 jected to various physical and chemical tests. We learn from 

 such experiments that anything that helps the oxidation in 

 general, such as alkaline media, moisture, agitation, heat, etc., 

 also facilitates the phosphorescence of the material; while, on 

 the other hand, exposure to carbon dioxide stops it. The pho- 

 togenic material is formed as the result of metabolism in the 

 cell, and in the process of its formation is identical with that 

 known as secretion. 



Before we go any further into our subject a few words are 

 needed on the use of the term " secretion," with special refer- 

 ence to the formation of photogenic material in phosphores- 

 cent organisms, because, as I shall point out more fully later, 

 it was the narrow, limited use of the term that impeded the 

 better understanding of the phenomena of phosphorescence as 

 a whole. 



Secretion, as popularly understood, suggests the existence of 

 a gland, secreting a material which is eventually discharged 

 from the organism, as is familiarly seen in the secretion of 

 saliva, mucus, or poison of various kinds in different organ- 



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