NOMAD l'UN(iI. 117 



myoeliiun, whicli lias produced iiredo-spores all the anmmer, begins in 

 autumn (influenced doubtless by the gradual ripening of the tissues of 

 the wheat) to give off the puccinia-spores, whicli are not only two- 

 celled — an unimportant circumstance * — but are distinguished by their 

 thick cuticle, that peculiar dense waxy layer whicli the external 

 lamina) of the cell-wall have the power of secreting if they wish to 

 protect themselves against heat or cold. It is this layer which gives 

 to a sorns of puccinia-spores its strikingly shiny aspect. Clothed in 

 this extra garment, they lie snugly ensconced in the half-decayed 

 tissues of their host, uiichilled liy wintry blasts, until the warnitli of 

 returning spring calls forth again the leaves upon which they are fitted 

 to grow. In the case which we are considering the leaves for which 

 they wait are those of the common barberry. 



Here, however, is another difficulty. The puccinia spores are large 

 and heavy — the hoplites of the fungal army ; moreover, they are firmly 

 attached to the basidia from which they spring, and not readily 

 detached, as in the two other kinds. The wind and the rain can do 

 but little to effect the transference of such a heavy brigade of spores as 

 these from the surface of the ground to the young barberry leaves, 

 which alone can furnish the requisite nidus. If the fungus had not 

 still another resource in store, if it were now at its wit's end, the 

 farmer might breathe a sigh of relief, for perhaps his crops would 

 never be attacked by rust or mildew again. But all is not yet lost : 

 the fungus is equal to the occasion. Each cell of a puccinia-spore. 

 germinating where it lies, sends out a short tube, forming at the end a 

 few branches (usually two to four), into which the protoplasmic con- 

 tents of the cell pass ; the ends of these branches are constricted off, 

 and we get two or three little round spores (the so-called sporidia), 

 which ai'e admirably adapted for being blown by the wind wheresoever 

 it listeth. Imagine one of these tiny spheres alighting on a barberry 

 leaf ; it germinates, sending out a germ-tube as before, but this time 

 the tube does not seek for a stomate, but bores its way straight through 

 the tender cuticle into the leaf. Here it forms a mycelium, from 

 which, after a week or two, the CEcidium is again produced. 



Thus the life-cycle is complete, and I venture to say that we have 

 here as nice an instance of adaptation of means to ends, and as strange 

 a story of transformation, as any which biology can furnish. This 

 romantic tale is founded upon fact. Puccinia-spores have been sown 

 upon barberry leaves and observed to germinate, and from the myce- 

 lium thus produced an fficidium has been seen to grow; \ similarlv 

 the production of the UreJo from the cecidio-spores has been actually 

 watched, while the production of a Puccinia from the same mycelium 

 as the Uredo is a matter of easy observation. Thus, as in so many 

 other instances, a common belief of country people, after enduring 

 from so-called men of science the customary stages of incredulity and 



♦ This is shown by the fact that in the genus Uromyces, which is in every 

 respect analogous to Puccinia, these spores are one-celled. 

 t " Grevillea," .xi. pp. 54-6. 



