Polytechnic Association. (549 



archon that receives the intelligence ; and we suppose it is lodged in 

 the brain. We know that we are duplicated throughout ; two eyes, 

 two hands, two halves of the nose, and so we have two brains. But 

 we have a great many brains. There is the great solar plexus, for 

 instance, behind the stomach. But we have a class of beings with no 

 brain at all, which act with as much discretion as a man. The spider 

 has no brain at all ; and I have watched them as they worked. I 

 have discovered that they are right-handed, working better with the 

 right hand than with the left. It was certainly acting with reference 

 to the attainment of an end, when they have tried the different cords 

 of their web to see which was slack, and then mended that' which was 

 broken. 



The President — It may be questioned wh*ether the action of the 

 spider is not the result of the education of a great many spiders as 

 predecessors ; whether instinct is not really the education of all their 

 progenitors. 



Dr. J. W. Richards — The brain is only one large ganglion or con- 

 geries of ganglia, similar to the little ganglia that are scattered all 

 over the body. It is not necessary that the functions of the brain 

 should be confined to one organ in all animals. 



The President — The skull itself is only an expansion of the upper 

 j< int of the back-bone. 



Dr. P. H. Tan der Weycle — A spider has brains. Agassiz ascribes 

 brains even to the oyster. A spider has eyes, and therefore an optic 

 nerve. "Where does the optic nerve go to, if not to the brain ? 



V. Plants Killed by Fkost. 



Professor Gceppert, of Breslau, has satisfactorily shown that in 

 certain cases plants die in freezing and not in thawing. The white 

 flowers of some orchids change in color upon a chemical reaction 

 which takes place on the death of the parts. When crushed, or when 

 the vitality of the cells is in any way destroyed, they turn blue 

 immediately. Cold may produce a similar result. These flowers 

 turn blue at once on freezing, showing that life has departed. 



Dr. D. D. Parmelee inquired what was the cause of the action of 

 the sensitive plant. 



Dr. P. H. Van der Weyde — On the back of the leaf is an organ of 

 blown color, which contracts when it is shaken, causing the leaf to 

 close. If that is cut off, the plant is no longer sensitive. 



Dr. J. J. Edwards — It is not one plant alone that is sensitive. 

 Every plant follows out its own nature as much as the sensitive plant, 



