188 



30, had pronounced in favour of the Schwenderian theory (passage 

 read), which was strongly endorsed by Sachs, and confirmed by the 

 results obtained by Bornet, Bees, and Stahl, who, proceeding synthe- 

 tically, sowed Lichen spores on or near Algas, and obtained thereby 

 true Lichen thallus, and not only that, but in the case of the latter 

 observer, it was demonstrated that the same Alga in connection with 

 different Ascomycetes produced different Lichens. It might be of in- 

 terest to the meeting if he were to describe briefly some investigations 

 which had recently been undertaken by Mr. Babikoff and presented to the 

 St. Petersburg Academy. If certain Lichens were examined, there would 

 be found upon them oblong or orbicular tubercles, consisting for the most 

 part of masses of gonidia, which were known under the name of Ceplia- 

 lodia. It had been suggested some years ago that these were an abnormal 

 formation produced by algae which had accidentally fallen upon the surface 

 of the Lichen, and it was to ascertain the correctness of this view that 

 M. Babikoff made a study of the whole life-history of the Cephalodia. By 

 cultivating the gonidia, he found that they consisted of Nostoc containing 

 Phycochrome, those of the Lichen itself containing Chlorophyll, and he was 

 able to follow the progress of development from the earliest period down 

 to the mature state of the Cephalodia. Mr. Crisp then, by drawings in 

 coloured chalks, made by Mr. Stewart on the black board, showed (1) the 

 commencement of the development of the Algas by ramified hairs of the 

 surface of the Lichen ; (2) the stage of complete development, the hypha 

 of the Lichen forming a continuous tissue with the Cephalodia, and the 

 gonidia interrupted beneath the latter; (3) the more advanced stage 

 showing the disappearance of these gonidia, and the conversion of the 

 tissue of the Lichen beneath the Cephalodia into very interlaced hypha, 

 which degenerate lower down into Bhizines ; and (4) the final stage of 

 separation of the Cephalodia from the Lichen. 



Mr. Charles Stewart said he had very few more remarks to make ; he 

 could only repeat what he stated at first — that he had but slight 

 practical acquaintance with the subject, though he certainly thought from 

 reading that the balance of evidence was in favour of the theory that 

 Lichens were cases of special Fungi parasitic on certain Algae. That 

 there should be some difference, he was quite prepared to find, but he 

 was not aware that there was after all any radical difference; and cer- 

 tainly on comparing the Gonidia with known Alga3 he thought that there 

 was a remarkable resemblance. He had been particularly struck in 

 examining the Lichens in the neighbourhood of London, where the com- 

 plete development of the tlialli (?) was arrested by the impurity of the 

 atmosphere. Finding from examination of these Lichens that the Hyphae 

 and associated algoid cells were exceedingly like the Hyphae of a Fungus 

 and known Alga, he naturally came to the conclusion that the circum- 

 stance was in favour of the dual nature of the Lichen. There were just 

 two other points which he would like to mention — one was with regard 

 to the mode of growth in Lichens ; sometimes the Alga element seemed 

 to be in greater proportion than the Fungoid, and then the growth was 



