CHAPTER IV 



REPRODUCTION 

 I. REPRODUCTION BY ASCOSPORES 



A. HISTORICAL SURVEY 



THE earliest observations as to the propagation of lichens were made by 

 Malpighi 1 who recorded the presence of soredia on the lichen plant and 

 noted their function as reproductive bodies. He was followed after a con- 

 siderable interval by Tournefort 2 who placed lichens in a class apart owing 

 to the form of the fruit: "This fruit," he writes, "is a species of bason or 

 cup which seems to take the place of seeds in these kinds of plants." He 

 figures Ramalina fraxinea and Physcia ciliaris, both well fruited specimens, 

 and he represents the " minute dust " contained in the fruits as subrotund 

 in form. The spores of Physcia ciliaris are of a large size and dark in colour 

 and were undoubtedly seen by Tournefort. Morison 3 , in his History of 

 Oxford Plants, published very shortly after, dismissed Tournefort's "seeds" 

 as being too minute to be of any practical interest. 



Micheli 4 , with truer scientific insight, made the fruiting organs the subject 

 of special study. He decided that the apothecia were floral receptacles, 

 receptacula florum, and that the spores were the " flowers " of the lichen. He 

 has figured them in a vertical series in situ, in a section of the disc of Solorina 

 saccata* and also in a species of Pertusaria*, in both of which plants the 

 ascospores are unusually large. He adds that he Had not so far seen the 

 " semina." 



Micheli's views were not shared by his immediate successors. Dillenius 6 

 scarcely believed that the spores could be " flowers " and, in any case, he 

 concluded that they were too minute to be of any real significance in the 

 life of the plant. 



Linnaeus 7 , and after him Necker 8 , Scopoli 9 and others describe the apo- 

 thecia as the male, the soredia as the female organs of lichens. These old 

 time botanists worked with very low powers of magnification, and easily went 

 astray in the interpretation of imperfectly seen phenomena. 



Koelreuter 10 , a Professor of Natural History in Carlsruhe, who pub- 

 lished a work on The discovered Secret of Cryptogams, next hazarded the 

 opinion that the seeds of lichens originated from the substance of the pith, 

 and that the overlying cortical layer supplied the fertilizing sap. Hoffmann" 



1 Malpighi 1686. 2 Tournefort 1694. 3 Morison 1699. 4 Micheli 1729. 



5 Micheli, Pis. 52 and 56. 6 Dillenius 1741. 7 Linnaeus 1737. 8 Necker r77i, p. 257. 



9 Scopoli 1772. 10 Koelreuter 1777. " Hoffmann 1784. 



