OiV THE NATURE OF CELL-ORGANIZATION. 89 



Now, this morphological criterion of an organ, which 

 necessarily relates to the history and mode of its origin within 

 tJie organism, by tJic differentiation of its parts, does not apply 

 to the chromatophore in a green plant, nor to the "gonidia" 

 in a lichen thallus, although there can be no doubt whatever 

 that these structures serve as organs in the physiological sense, 

 in the respective organisms. The chromatophores are not 

 the products of differentiation of an homogeneous germ of 

 the plant. They can only originate by the division of pre- 

 existing chromatophores, if we follow such botanists as Schmitz, 

 Schimper and Meyer. 1 The colorless protoplasm of the plant 

 and the chromatophores are the coexistent but independent 

 structures, with no genetic connection between them. 



In the organization of a lichen, the case is clearer and more 

 to the point of our inquiry. As is well known, the "gonidia" 

 and their supporting meshwork are derived from two different 

 groups of plants, viz., Algce and Fungi, respectively, although 

 their physiological adaptation to each other is so perfect, so 

 much so, in fact, that in several lichens the hyphae of the 

 fungus cannot live when separated from the algal portion, the 

 "gonidia." Here, again, it is needless to say that these two 

 organs are not the products of differentiation from some homo- 

 geneous an/age as different organs are in one of the complex 

 animals. 2 On the other hand, the "gonidia" of one individual 

 lichen are genetically related to the "gonidia" of another, and 

 not at all to the hyphae of the thallus. In a similar way the 

 hyphae of one individual lichen are genetically related to the 

 hyphae of another lichen of the same species, and not to 



1 Schmitz : Die Cliroinatophoren der A I gen, Bonn, 1882. Schimper : Ueber die 

 Entivickclung der Chlorophyllkoruer mid Farbkorper, Bot. Zeit., 1883, 41. Jahrg. 

 Meyer : Ueber Krystalloide dcr Trophoplastcn nnd ilbcr die Chromoplasten der 

 Angiospermen, Bot. Zeit., 1883, 41. Jahrg. 



- Before the discovery of the true nature of lichens, it was thought that both 

 "gonidia" and supporting fungal hyphae were the products of development of a 

 single germinating spore. " Gonidia," which are the symbiotic algal cells, were 

 supposed to be, as the term indicates, asexual organs of reproduction produced 

 from the hyphae and capable of development into a new and perfect lichen-thallus. 

 The view that hyphae might also be produced from the "gonidia" was often 

 expressed. De Bary, Historical Xotice of the Lichens. Comp. Morphology and 

 Biology of Fungi, etc., p. 416. 



