,1882.] 



MICKOSCOPICAL JOUEISAL. 



35 



readily enough accept the numerous 

 other instances of polymorphism af- 

 forded by the fungus kingdom, and 

 yet be unable to credit that a parasi- 

 tic fungus can commence its life on 

 one plant and finish it upon another, 

 especially when the host plants are so 

 far removed from one another, that 

 the one is an exogen and the other 

 an endogen. But this alternation of 

 generation is well known to exist in 

 other departments of the organic 

 world, amongst organisms far higher 

 in the animate scale than cryptogams. 

 To take a well-known example af- 

 forded by the £ntozoa, the Tenia 7ne- 

 diocanellata, Kiich, commences its ex- 

 istence in the flesh of the ox, as Cy- 

 sticercus bovis^ and finishes it in the 

 alimentary canal of man; or Tenia 

 solium, Linn., which commences its 

 existence as Cysticercus celluoscR in the 

 flesh of the pig, and finishes it in the 

 same situation as the first mentioned 

 cestode. 



There exists a widely spread super- 

 stition amongst agriculturists, which 

 was credited far more extensively by 

 the past generation of farmers than it 

 is now, that the presence of a bar- 

 berry bush was connected with the 

 occurrence of mildew in wheat. So 

 much was this the case that in most 

 parts of Norfolk the barberry {Ber- 

 beris vulgaris) has, to a great extent, 

 been exterminated. Now, nothing 

 tends more to render a statement in- 

 credulous to people in general and to 

 scientific minds in particular, than to 

 brand it with the title of superstition. 

 We dislike above all things to be 

 thought superstitious, it is derogatory 

 to our intellectual status. Without 

 entering upon the question generally, 

 of whether most superstitions have 

 not a strain, however meagre, of truth 

 underlying them, this sentiment has 

 not been without considerable influ- 

 ence in rendering us chary of accept- 

 ing the heteroecism of Puccinia gra- 

 minis. It must, however, be borne in 

 mind that the connection of barberry 

 bushes with mildewed wheat presum- 

 ably arose, as a matter of observation 



on the part of our forefathers, when 

 they suffered from the pest. 



Leaving the sesubsidiary considera- 

 tions, and for the moment discarding 

 the element of heteroecism, let us 

 consider whether there be any impos- 

 sibility in the yEcidia generally being 

 the earlies states of certain Pucmiice. 

 It is presumed that no one now doubts 

 the connection of the majority of 

 Uredines with Piucinice, and it must 

 be borne in mind that a much greater 

 difference existed in form, color and 

 spore structure between Puccinia and 

 Uredo than is the case with ALcidiitm 

 and Uredo. The free spores of many 

 species of ^cidiuni cannot be distin- 

 guished from the spores of many Ure- 

 dines. ALcidium as a genus differs 

 from the ^^Vv^/i? principally in the pos- 

 session of spermogonia, of a peridium, 

 but more particularly in producing its 

 spores in chaplets. All yEcidia, how- 

 ever, do not possess spermatia, for of 

 the thirty-two species enumerated as 

 British in the " Handbook," the pres- 

 ence of spermogonia is only noted in 

 four; while certain Ur dines are pro- 

 vided with them, e. g., U. suaveolens, 

 Pers., U. orc/iidis, Mart., U. gyrosa, 

 Rebent, U. mercurialis, Link., U. 

 Euonymi., Ma.rt.,a.nd U. J>ing7a's, D. C. 



Sir John Lubbock, in his address 

 to the' British Association at York, 

 last August, has very pertinently said, 

 " Naturalists are now generally agreed 

 that embryological characters are of 

 high value in classification," the truth 

 of which assertion is daily becoming 

 more and more accepted by students 

 of Natural History. 



Now when we cause the spores of 

 yEcidia to germinate under circum- 

 stances in which we can watch the pro- 

 cess, we find they do so in exactly the 

 same manner as Uredo spores, namely, 

 by the protrusion of a hyaline tube 

 through the epispore. This hyaline 

 tube gradually elongates, and into it 

 are emptied the contents of the spore, 

 which are passed onwards until they 

 eventually reach the end of the tube. 

 This tube (or tubes, for there may be 

 more than one) undergoes in both in- 



