48 PROCKEUINCiS t)l- Tin; 



l)y the L'xliaustioii of his resoiirci's, wliicli involved a, i-ftuni to 

 schoi)l-k'achiiig. ilowever, in 1856, lie was in a position to remove 

 to Ziiric-h to resume botanical work under Oswald Jleer, and in 

 that year he j^raduated with a pha-nological thesis, ' Leber die 

 .periodischen Erscheinungen der S'atur, insbesondere der Ptlanzen- 

 welt," which he had begun at (Geneva. 



Scliwendener soon came into relation with Xaegeli, who had 

 recently moved to Ziirich from Freiburg i./B., and with his assist- 

 ance began the study of the microscopical anatomy of plants, 

 'i'he result was that when Naogeli was called to the Professorship 

 of Botany at Munich (1857), .Schwendener accompanied him as 

 his assistant. After ten years at Munich, Schwendener was 

 .jippointed Professor of JJotany at Basel : ten years later (1877) 

 he moved on to Tiibingen, where he succreded Hofmeister; and 

 in 1870, on the death of Alexander Braun, he became Professor 

 of Botany at Berlin, where he spent tiie lemainder of liis life. 

 He died on 27th May, litl!*. He was never niarried. 



His first considerable work was ' Has ^likroskop,' written in 

 collaboration with Xaegeli, i)ublished 18(55-7 (l^nd edn. 1877), a 

 book which contributed materially to tlie development of modern 

 Botany. Schwendeiier was especially I'esponsible for the part of 

 it dealing with the mechanisMi and the optical theory of the 

 microscope ; he discharged his responsibility with conspicuous 

 success that showed the natural bent of his mind to the mathe- 

 matical. As a matter of fact, Schwendener was not a naturalist, 

 and was rather contemptuous of systematic Botany and field-work. 

 However, at this period he was actually engaged upon a piece 

 of definitely botanical work, investigating the structure of 

 Lichens, the results of which were published in Naegeli's 'Bei- 

 triige zur wisschenschaftlichen Botauik,' 18t)0-3-8. At that 

 time much interest was being taken in the nature of tlie coloured 

 cells containing chlorophyll, known as "gonidia," which are a 

 •constituent of the Lichen-thallus. The resemblance of these 

 gonidia to free-living organisms considered to be Algae was 

 recognised, and the |)revalent view was that these so-called Algae 

 were merely Lichen-gonidia which had escaped from the thallus 

 and continued to live as free organisms. The conjecture had 

 been hazarded that the facts could be interpreted in ])recisely the 

 opposite way : that the gonidia are really Algaj which have 

 become enclosed by and imprisoned in the colourless filamentous 

 tissue of the growing Lichen-thallus. Schwendener was led by 

 his observations to adopt and .support the latter \iew. In 1869 

 he jjublished his celebrated work, 'Die Algentypen der Flechten- 

 gonidien," in which he adduced convincing t-vidence that the gonidia 

 do not originate in the thallus, but are Al^iaj which have become 

 invested or invaded by the mycelium of a Fungus. This led on 

 to the striking inference that a Lichen is not a siinple organism, 

 but is con)posite, consisting of Algae and Fungus living together 

 in a relation which, on the whole, is one of nuitual advantage — 

 an altogether new biological conception which de Bary termed 



