40 SURVEY OF THE REPRODUCTIVE PROCESS 



top of the central sac, which developes downwards into 

 rootlets and upwards into stem.* 



The Characese multiply also by deciduous leaf-buds ; but 

 we are very deficient in observations regarding the develop- 

 ment of this singular group of plants. 



5. REPRODUCTION IN FUNGI AND LICHENS. 



The Fungi are a large order of aerial cellular plants of 

 low development, intermediate between Algse and Lichens, 

 and passing into both orders by the closest possible affini- 

 ties. In their structure there is generally a very marked 

 distinction between the vegetative tissue and the reproduc- 

 tive organs ; the former, termed the mycelium, is always 

 the most inconspicuous, and frequently escapes observation 

 altogether, being embedded in the soil or basis on which 

 the fungus grows. It consists of a mass of branched con- 

 fervoid filaments, inextricably entangled, and frequently 

 even anastomosing together. 



The vitality and vegetative power of these filaments is so 

 great that even fragments of them will suffice to reproduce 

 the mycelium. Such fragmentary portions are indeed pro- 

 fusely detached as gemmae in the normal development of 

 the tissue ; and as the particular form and connections 

 of these reproductive bodies vary at different periods of the 

 life-history of the plant, we meet with a great variety of 

 fructification even on the same species ; as many as five 

 different forms are stated, on the authority of Mr Berkeley, 

 to occur in the same species of Erysiphe.-^ As the specific 

 identity of these forms, depending on their connection with 

 the same mycelium, may readily escape observation, it is 

 not wonderful that many of them figure as distinct plants 



* Berkeley, Op. Cit., p. 428. Carter in Ann. Nat. Hist., 2d Ser., 

 XVIIL, 107. 



f Cryptogamic Botany, p. 78. Quarterly Journal of Microscophic 

 Science, Jan., 1857, p. 54. 



