118 POTATO DISEASE. 



made to Mr. Luff on September 27th we noticed the complete 

 failure of his tomatoes. 



Our paper published in 1845 was illustrated by some micro- 

 scopic drawings of sections of diseased tubers, and in these it 

 now appears that we had detected what Mr. Smith has figured 

 as the Oogonium, egg, or resting spore of the Peronospora.* This, 

 however, at that time we provisionally named Uredo tulerosum, 

 which name we prefaced with the following remark : 



"From our microscopic observations we come to the conclu- 

 sion that the affected potatoes of the present season (1845) con- 

 tain innumerable fungi, similar in every respect to many species 

 of the low genus of Cryptogamous, or flowerless plants, called 

 Uredo." 



"We were then young in the use of the microscope, and had 

 not a very perfect instrument, but we are pleased to find that 

 although we did not examine the leaves and haulm of the 

 potato at the time that we were still the first to figure its appear- 

 ance in the tuber. The truth is that even so far back we almost 

 advocated the theory that the attack on the leaves and haulm was, 

 as far as we could then see, a result, and not the real cause of 

 the affection. We then thought, and have not yet quite got rid 

 of the heresy ? that mildew and blights so called were results of 

 cold rains and want of sunshine, and we quoted at that time Pro- 

 fessor Lindley in support of our opinion, that is, that the mildew 

 was rather an effect of weather and surrounding circumstances 

 than a cause of potato disease, and " almost all decaying veget- 

 ables are attacked by some species of Uredo, or an allied fungus 

 which appear to differ with each species of plant, hence they are 

 conceived by some to be a metamorphoses of the cellular tissue. 

 Lindley says of those low fungi, " It is uncertain whether they 

 are not a mere representation of the vital principle of vegetation, 

 capable of being called into action either as a fungus, an alga, 

 or a lichen, according to the particular conditions of heat, light, 

 moisture, and medium in which it is placed; producing fungi 

 upon dead or putrid organic beings ; lichens upon living vege- 

 * Engiaving C. 



