62 BORDER LINES OF KNOWLEDGE 



cochlea of the ear, had done more to clear up its doubt- 

 ful physiology ; but I am afraid we have nothing but 

 hypotheses for the special part it plays in the act of 

 hearing, and that we must say the same respecting the 

 office of the semicircular canals. 



The microscope has achieved some of its greatest 

 triumphs in teaching us the changes which occur in the 

 development of the embryo. No more interesting dis- 

 covery stands recorded in the voluminous literature of 

 this subject than the one originally announced by Mar- 

 tin Barry, afterwards discredited, and still later con- 

 firmed by Mr. Newport and others ; namely, the fact 

 that the fertilizing filament reaches the interior of the 

 ovum in various animals ; — a striking parallel to the 

 action of the pollen-tube in the vegetable. But beyond 

 the mechanical facts all is mystery in the movements 

 of organization, as profound as in the fall of a stone or 

 the formation of a crystal. 



To the chemist and the microscopist the living body 

 presents the same difficulties, arising from the fact that 

 everything is in perpetual change in the organism. The 

 fibrine of the blood puzzles the one as much as its glob- 

 ules puzzle the other. The difference between the 

 branches of science which deal with space only, and 

 those which deal with space and time, is this : we have 

 no glasses that can magnify time. The figure I here 

 show you* was photographed from an object (^pleuro- 



• From a very interesting paper by Professor 0. N. Rood, of Albany, 

 containing, with other views, the first microscopic stereograph I have seen. 



