49 



CHAPTER VII. 



PEOPAGATION OF FUNGI. 



Fungi are propagated by cells, Avliicli either separate by- 

 means of a constriction from privileged portions of their 

 tissue {spores) (Plate 1, fig. 1), or are pi'oduced freely [spo- 

 ridia) within certain sacs called asci (Plate 1, fig. 2) or spo- 

 rangia. In a few exceptional cases, though attached to the 

 tips of the fruit-bearing threads, they arc surrounded by a 

 common membrane (Plate 1, fig. 3, 6) . Whether the repro- 

 ductive bodies, however, be called spores or sporidia, they 

 have a singular tendency to appear in definite numbers, either 

 in twos, fours, or multiples of four. Amongst the lower 

 sporiferous Fungi there is seldom any attempt at arrange- 

 ment; but in the higher, the sporophores almost uniformly 

 have four spicules, and each of these is surmounted by a 

 single spore. Very rarely there are but two, and still more 

 rarely, as in Phallus, the number exceeds four. Amongst the 

 sporidiiferous Fungi, the most common number of spoindia in 

 each ascus is eight ; where they are very large, this is some- 

 times reduced to four, and, on the contrary, sometimes in- 

 creased to sixteen, thirty-two, etc. In some cases the num- 

 ber is indefinite, and, as far as I know, amongst the Vesi- 

 culiferi always so. The same law docs not hold good when 



