511 



states that the coiiditioiiis of planting?, manuring;, and soil were practi- 

 cally the same in each case. Facts similar to these have frequently been 

 made from time to time, and form an imj)ortant point for investigation, 

 and conclusively show that the condititm of the potato itself has as much 

 to do with the rot as the fungus, Botri/tus infefitans. It Iihs been fre- 

 quently stated "that the i)otato, from high cultivation, has run out, and 

 that recourse should bo had to the seed of the phint as a means ot renew- 

 ing the crop." The terms, "high cultivation," if they have any practical 

 meaning, must signify that an internal organic structural change has 

 taken i)lace. It may be that the vascular bundles occupy a larger space 

 in the highly cultivated potato, so called, than they did when they first 

 became an object of public interest; if so, this alone might in part 

 explain one of the great causes of i)Otato-rot. U he fact that the disease 

 in the potato-plant always appears first in the vicinity of the vascular 

 bundles, or air-cells, would seem to fortify this idea, and investigations 

 in this line might prove protifable. 



An abundance of moisture and heat will produce rank growth. The 

 first structure formed is cellular, which includes the vascular bundles 

 or air passages, and other forms of cellular tissue. Nitrogenous cells 

 next follow, as a lining to cellulose cells, and, in the case of the 

 potato within this cell, again forms a second cellulose cell, which 

 becomes the starch-cell, and the more likely is this the mode of action, 

 from the fact that starch may be made from the nitrogenous mat- 

 ters, while from the former the latter cannot be made. It is self- 

 evident that the Jackson Whites, in the case alluded to, were proof 

 against the attacks ot fungi, although surrounded by it, and the inference 

 might be drawn that the Jackson VVhites seed was in a more favorable 

 coudition when jtlanted than was the Early Rose seed, and hence the 

 assimilatioifs of the plant were not retarded. Still, the unfavorable 

 climatic conditions luider which they grew would change in some degree 

 the relative organic internal structure. After several such changes were 

 effected under tlie coiulitions stated, viz, extraneous moisture and high 

 temperature, the Jackson Whites would probably be as liable to disease 

 as tlie other variety. Seed will not come to i)erfect maturity under 

 adverse conditions, especially plants that are very susceptible to climatic 

 changed. Seed of the same stock, attaining its perfect development 

 under more favorable conditions of sun heat and moisture, all other 

 conditions being equal, would probably give much more favorable results, 

 changing probably the relative proportions of the vascular bundle, &c.. 

 to the parenchyma cells. Judging from analogy, I am of oi)inion that 

 more attention should be paid to the climatic conditions under which the 

 seed was produced. Selections of seed made for a series of years from 

 favorable climatic districts would have a great tendency to produce that 

 healthy farm of tuber desired for seed purposes. The savans of Europe, 

 according to the English monthlies, have nothing better to offer as a 

 renfedy but the cutting off the stalks the moment the brown blotches 

 api)ear. The climate of Great Britain and Ireland, as a rule, is very 

 unfavorable for the growingof tubers fromseed. Theclinuiteisfrequently 

 extremely moist. Boirytus itifestans o\\ [)otato fungus is always present 

 in damp places, living on weeds, &c. ; its constant presence is well known 

 to micologists. Notwithstanding tliat Botrytus infestaiis is truly par- 

 isitic, its ravages are moditied by climatic conditions. 



