SYMBIONTICISM AND ORIGIN OF SPECIES 107 



level (Hemmeter, '26). The liver is known to have the 

 property of decomposing hemoglobin. 



The suprarenal gland, apparently, has the property of 

 producing adrenalin or epinephrin. Mathews ('15) states 

 that it has been claimed that certain bacteria have the 

 property of changing tyrosin into adrenalin. 



From this brief survey it is evident that many of the 

 products that are characteristic of certain speciaUzed cells 

 in higher animals are also the products of bacterial metabo- 

 lism. The basis for a correlation of this circumstance is 

 to be found in the bacterial nature of mitochondria. Sym- 

 bionticism offers a ready explanation for the origin of the 

 "speciaUzed cells" in the higher plants and animals. The 

 probabihty that Symbionticism is the factor concerned in 

 the acquisition of these specialized properties, is enhanced 

 by the results of a number of mitochondria investigators. 

 Regaud and Mawas ('09) concluded that the secretions of 

 the parotid and submaxillary glands originate from the 

 mitochondria. Prenant ('13) associated pigment forma- 

 tion wdth mitochondrial activity; Mulon ('10) concluded 

 that the secretion of the suprarenal glands originates from 

 the mitochondria; Hoven ('10), Horning ('25) and others 

 believe that zymogen of the pancreas originates from mito- 

 chondria. Other cell products and structures that have 

 apparently originated from mitochondria are catalogued in 

 Chapters II and IV. 



Modem researches in the plant kingdom have revealed 

 some significant developmental activities. Our interest is 

 especially directed to the chloroplasts and other plastids. 

 Practically all green plants — the Bnjophyta, Pteridophyta 

 and Spermatophyta, as well as the lowly algae — ^possess 

 chloroplasts which in turn contain chlorophyl. The Cyano- 

 phyceae (Schizophyceae) , or blue-green algae contain no 

 chloroplasts. In these forms, the chlorophyl and the blue- 

 pigment (not always blue, the characteristic hue of the 



