DREAMS AND THE MAKING OF DREAMS. + 6i 



Adult water-insects carry air into the depths of the water by hold- 

 ing it under the wings or legs, or by the minute hairs which cover the 

 body. This frequently gives them the silvery appearance of a globule 

 of mercury, and sometimes renders the creature so buoyant that it has 

 to descend by muscular effort swimming downward, or crawling down 

 a plant-stem. 



Insects of powerful flight have sacs developed on the trachea?, which 

 doubtless serve to store air, and also to render the body lighter. 



Spiders lack the tracheae, but have the spiracles opening directly 

 into sacs. These are various in structure, sometimes folded like gills, 

 or in other cases cellular, like a rudimental lung in structure. 



Among mollusks only the true snails are air-breathing, and some 

 of these inhabit water. They have organs resembling those of the 

 spider, concentrated into a single sac. This is lined with blood-capil- 

 laries and constitutes a true external lung. The orifice opens on the 

 right side of the neck, and can be closed by a circular muscle. 



In the pond-snails we have a clear illustration of the identity in 

 principle of air and water respiration. For, in the Lymnece, the sac, 

 which in the early stages of the animal breathes water alone, can sud- 

 denly change to a lung, and thereafter breathe only air. And in speci- 

 mens from deej) water the change may occur in the adult animal. The 

 AmpuUariCB have the breathing-sac partially divided into an upper or 

 air chamber and a lower or gill cavity ; using first one and then the 

 other, or breathing air and water alternately at intervals of a few 

 minutes. 



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DREAMS AND THE MAKING OF DREAMS. 



By J. MORTIMER GRANVILLE, M D. 



DREAMS are night-thoughts, unchecked by the judgment and un- 

 controlled by the will. It is not true that we do not reason in 

 dreams, that the exercise of the judgment is wholly suspended, and 

 that the will is entirely powerless or ceases to act. These faculties 

 are not altogether in abeyance, but they doze while the subordinate 

 powers of the mind those which play the parts of picture-carriers and 

 record-finders ransack the treasures of memory and mingle together 

 in the direst confusion old things and new. Imagination is not active, 

 but it remains just enough awake to supply the connecting links which 

 give seeming continuity to those parts of the phantasmagoria which 

 we chance to remember on recovering perfect self-consciousness, and 

 which, being remembered, we call " dreams." No one remembers 

 more than one dream, unless he has roused from sleep more than once. 

 This experience has led to the inference that dreams only occur at the 



