2''i2 



THALLOPHFTES. 



erect hairs. The walls of the hyphae of this part assume a dark colour, but the inner 

 tissue remains colourless (Fig. 175, ^); its apex increases in breadth, the hairs separate 

 from one another, and the outer peridium ceases to exist at the apex (Fig. 176, ap). 

 In the meantime the differentiation of the tissue commences in the interior of the 

 Fungus, ^^'hich is at first formed of densely-woven much-branched hyphae, enclosing 

 amongst them a considerable quantity of air which gives the whole a white appear- 

 ance. Certain portions of the air-containing tissue become mucilaginous and freed 

 from air ; between the threads is formed in some places a hygroscopic transparent 

 jelly, while in others none is produced. The conversion into mucilage begins first 

 below the surface of the white nucleus (Fig. 175, v^), and its outer layer is thus trans- 

 formed into an inner peridium which is a colourless sac protruding from the dark outer 

 peridium, and composed chiefly of branches of hyphae running longitudinally upwards 

 (Figs. 1 76 and 177, //>). While this differentiation is proceeding from below upwards. 



riG. 175. — Crucihulum viilgare; A, B, C m 

 longitudinal section (slightly magnified) ; D 

 the entire plant nearly mature (natural size). 



" / 



Fig. 176. — Crucibiihint vulgare; longitudinal section through the upper 

 part of a young receptacle (x about the same as Fig. 175, B). The section 

 is seen by transmitted light ; the dark parts in the interior are those 

 where air occurs between the hypha; ; at the light parts a transparent 

 mucilaginous substance free from air has formed between the hyphjE. 

 The light parts of this figure are dark in the previous one. 



small mucilaginous areolae form at certain points in a deep layer of the white air-contain- 

 ing nucleus, also proceeding from below upwards, like all the succeeding differentiations 

 (Fig. 175, B, and Fig. 176). The formation of mucilage advances at the same time from 

 the inner peridium inwards, and leaves round each of the mucilaginous areolae a border 

 of air-containing tissue (Fig. 176), which afterwards developes, by the dense interweaving 

 of its branched hyphae, into a firm envelope consisting of two layers, in which the muci- 

 laginous areola lies. For want of a better term, it may be called the Sporangium. While 

 the centre of the Fungus is becoming changed into mucilage, the sporangia grow into 

 lenticular bodies ; a mucilaginous point has appeared at an early stage on the lower and 

 outer part of each sporangium, and forms its umbilicus. From it a denser bundle of 

 threads runs downwards to the peridium, the umbilical bundle (Fig. 176, «, and Fig. 

 177, ns) ; this is itself surrounded by a conical bag {t) which surrounds the bundle like a 

 loose sheath. This sheath eventually becomes mucilaginous ; the bundle runs upwards 

 into the mucilaginous depression of the umbilicus, where it is resolved into its threads 

 which are now more loosely connected. The mucilaginous tissue in the interior of each 

 sporangium disappears, leaving a lenticular space similar in form to the sporangium itself; 



