68 Sl^BIONTICISM AND THE ORIGIN OF SPECIES 



origin. Siebold in 1849 declared that if the green material 

 of animal cells is not identical with chlorophyl, it is, at 

 least, very closely related to it. Max Schultze, a little 

 later, by means of chemical tests, definitely established the 

 similarity of plant and animal chlorophyl. The question 

 then turned to the origin of chlorophyl in the animal cell. 

 A number of investigators (Geddes, Lankester, Kleinen- 

 berg, McMunn, and others), declared for an animal origin 

 of the chlorophyl in the cells of animals. The bearing 

 that this interpretation had upon the much discussed "dif- 

 ferences" between plants and animals, stimulated a large 

 number of biologists to investigate the problem. Cien- 

 kowsky, in 1871, was the first investigator to present 

 evidence of the "parasitic" nature of the chlorophyl bodies. 

 He described the cellular nature of these bodies with their 

 nuclei, starch granules, and cell membrane. He also 

 observed that the chlorophyl bodies continued to live after 

 the death of the animal host. R. Hertwig, Brandt and 

 later Geddes, brought forth evidence in favor of the sym- 

 biotic nature of the chlorophyl bodies. They were shown 

 to be symbiotic algae. Brandt named the green forms 

 "Zoochlorellae" and the yellow-brown bodies, "Zooxan- 

 thellae." 



Microsymbiosis in which single-celled plants are the de- 

 finitive symbionts, apparently, has not persisted in the 

 higher groups of animals. It would appear that nature 

 stopped experimenting in this direction long before the 

 higher mammafia came into existence. Still it appears 

 probable that the fruits of these "experiments" have not 

 been entirely lost to the higher animals. The similarity of 

 chlorophyl and hemoglobin is suggestive of a possible origin 

 of hemoglobin from chlorophyl or a closely related sub- 

 stance. This possibihty is particularly enhanced when it 

 is viewed in the fight of Symbionticism. However, on 

 account of their greater famifiarity and the known physio- 



