1847.] Blight in Jlpple and Pear Trees. 5 



one-celled. In the cabbage, for example, on the other hand, we 

 find a two-celled pod, with the seeds attached to the wall, which 

 is a departure from theoretical principles, but the dividing mem- 

 brane we find not to be a part of the leaf, but an excessive devel- 

 opment of the placenta, forming a spurious dissepiment, as bota- 

 nists call it. 



Sometimes, we said, that we found seeds spread over a surface. 

 This is well exhibited in the pomegranate, and this fruit, by the 

 way, affords a most interesting object of study, and of which we 

 shall make special use in a iuture number. The placenta in the 

 pomegranate is spread over a large space, and folded on the in- 

 flected portions of the carpellary leaves, and hence we have seeds 

 apparently borne by all the interior surface of the seed vessel. 



To enter on the principles of classification of fruits, or to discuss 

 questions of vegetable physiology in regard to points we have as- 

 sumed as true, which have nevertheless been subjects of discussion 

 with botanists, would exceed the limits you would wish to af- 

 ford to this department of scientific research, and we shall leave 

 this topic after exhibiting the changes which the ovule undergoes 

 from its earliest stage to that of its perfect development, which 

 we will do by the aid of figures in our next. 



BLIGHT IN APPLE AND PEAR TREES. 



The search for causes in many of the phenomena of nature often 

 results in casting more perplexity and doubt over a subject of en- 

 quiry than existed at the outset of examination. We commonly 

 possess some vague notions of a cause, which is a support to the 

 mind for the time being, and blunts in a measure those unpleasant 

 sensations which are always experienced w^hen we are compelled 

 to feel that the cause is totally incomprehensible and beyond the 

 reach of our grasp. 



Many undoubtedly have felt a degree of complacency in their 

 supposed knowlenge of the potato disease, previous to their inves- 

 tigations of the matter, but we feel certain that many have closed 

 them with a feeling of great disquietude, and have been obliged 

 to acknowledge, to themselves at least, that the cause is in total 

 darkness; an acknowledgment which is never made without ex- 

 periencing painful emotions. It forms no part of our object to 

 account for this fact, or to show more than that our inability to 

 comprehend many of the common phenomena of nature is attended 

 with painful sensations. We have no doubt many persons, if they 



