1S46.] Report of Commissioner of Patents. 83 



its mode of development, have often been ccifonnded together, or 

 mistaken one for the other. 



4th. That there is great reason to doubt whether the immediate 

 effects of the latent cause have been so far subject of observation, 

 that an accurate and sure opinion can be formed respecting it. 



5th. That, whatever be the cause, there are different stages of 

 its development — degrees of its power ; and that these tlepend 

 on a variety of adaptations in the circumstances of the crop. 



6th. That the rapidity oi development also corresponds with the 

 aid derived from extraneous circumstances; and hence some, if 

 not all of the evil results may be remedied. 



7th. That it is doubtful whether any remedy suggested has 

 been sufficiently tried to enable us to pronounce it a certain or 

 sure one. 



8th, That it is important to study more accurately the influence 

 of soil, seed, culture, temperature and condition of the atmosphere 

 on this crop; and that it is only by a series of carefid and discri- 

 minating observations that we can clearly decide on the probable 

 origin and most fitting remedy. 



9th. That many of the preventives or checks recommended 

 have, in their favor, so good proof of a degree of efficacy, that, till 

 better are discovered, they may be safely adopted, suitable regard 

 being had to the similar or different circumstances of their appli- 

 cation. 



We believe there has been, as usual, injury sustained to the 

 potato crop of the United States by the prevalence of ordinary 

 and common causes, such as must be expected, more or less, every 

 year. We do not doubt, also, that there has been an extraordi- 

 nary loss of this valuable product; but whether it be owing to 

 some before known cause, which, from the peculiarity of the sea- 

 son or some unknown circumstances, has exerted an unusual in- 

 fluence, and thus a new development, or to some hitherto unexpe- 

 rienced cause till within a short period past, we cannot say. 

 Whatever it is, its progress is not yet fully traced, and it is only 

 till more light is shed on the subject that we can confidently pro- 

 nounce in favor of any one theory; and it seems probable that 

 there is a combination of the views that have been suggested ne- 

 cessary, in order to account for its various phases, as we cannot 

 resolve all the great features into one, entirely independent of all 

 others. It so happens, however, that we have it in our power to 

 make a comparison as to the aspect of the evil among ourselves, 

 and in those countries where it has prevailed. 



