270 



HARD WICKE'S SCIENCE- GOSSIP. 



a close examination of this shows that it is furnished 

 with numerous joints or septa. If, therefore, any 

 reliance is to be placed upon the modern distinguish- 

 ing characters of the now living species of Perono- 

 spora and Pythium, as furnished by a septate or 

 non-septate mycehum, then the fossil parasite belongs 

 to Peronospora, and cannot belong to Pythium or 

 any of the Saprolegniere. The oogonia do not agree 

 with those of Cystopus. Within many of the fossil 

 oogonia of the group illustrated, the differentiation 

 of the protoplasm into zoospores is clearly seen ; but 

 if any doubt could exist as to the exact nature of this 

 differentiation, then other oogonia (or zoosporangia) 

 on the same slide show the contained zoospores with a 



especially with the same organisms belongino^ to 

 Peronospora infcstans. The contained zoospores are. 



'«^'«* 



Fig. 202. The Fruit of a Fossil Fungus {Pcronosj-orltcs aniu/narins) containing 

 zoospores z« i/Vrf as seen amongst the scalariform vessels of a Lepidodendron from 

 the Coal measures (enlarged 400 diam.). 



clearness not to be exceeded by any living specimen 

 of the present time. One of the most perfect groups 

 of these Palaeozoic bladders, containing the once- 

 mobile spores, is shown in fig. 202, enlarged to 400 

 diameters, and the wonderful fact becom.es manifest 

 that the bladder is exactly the same in size and 

 character with average oogonia of the present day, 



Fig. 203. Fruit of the Potato Fungus {Peronospora infcstans), 

 from the tuber of a potato, to show uniformity in size with the 

 fossil fungus (enlarged 400 diam.). 



moreover, the same in form and dimensions with the 



zoospores of Pcro)iosp07-a infcstans, when measured 



to the ten-thousandth of an inch. 



^■Jx;.':' . For comparison, an oogonium and 



&r#o-'' ^ group of free zoospores enlarged 400 



diameters, and belonging to the 



fungus of the Potato disease, is illus- 



^>; :•:■;•";;■;■:•' trated in fig. 203. On examination, 



it will be seen that the oi-ganisms are 



apparently identical. The average 



number of zoospores in each oogonium 



is also the same, viz., seven or eight. 



The aerial condition of the fungus has 



not yet been observed. 



' ' In Pcronospoi ites antiquariiis we 

 then, probably, have one of the simple 

 primordial plants of the great family 

 of fungi. The Peronosporce are 

 closely allied to the Algre — so 

 closely, indeed, that De Bary says 

 the species of the foraier may with 

 reason be compared with the species 

 of one group of the latter named, 

 the Saprolegniece ; other botanists ■ 

 place the Saprolegniere amongst true 

 fungi. If Peronospora is, therefore, 

 an Alga (and its extremely close 

 relationship is doubted by none), we 

 have in Pcronospo7-itcs antiquariiis a 

 plant which, from its extreme 

 antiquity, lends some favour to the 

 views of Sachs and other evolution- 

 ists. These observers place the lower 

 Algae amongst the primreval plants 

 from which fungi and all other cellular 

 Ciyptogams have branched. This 

 position is hardly invalidated by the 

 presence of the more highly-organised 

 vascitlar Cryptogams living at the 

 same period of time with the prim- 

 ordial Alga or fungus. 



"The evolution of animals and plants is quite 

 comparable with the ages of stone, bronze, and iron, 

 with reference to the different tribes of the human 

 family. Because the stone age dates back to dim 

 antiquity, it does not follow that it has entirely va- 

 nished from off the face of the earth. It is clear that 



