104 Journal of the Mitchell Society [Fehruanj 



3. All the naturally nephropathic animals become anuric in the 

 early stages of the experiment and remain anuric and non-responsive 

 to diuretic solutions throughout the experiment. 



A. W. HoBBS — Einstein's Special Relativity Theory. 



The laws of Nature must be invariantive, that is they must be 

 so stated as not to depend upon any particular frame of reference. 

 All attempts to discover different values for the velocity of propaga- 

 tion of light in different directions have failed. We then assume the 

 constancy of the velocity of hght. This leads to the conclusion that 

 x^+y^+z-— C't^ must be changed into the same expression when we 

 refer to another system (i. e.) x^+y^-f-z- — c-t^ = x'2-fy''' + z'2— c^t'^. 

 The Lorentz transformation accomplishes this and is at the same 

 time consistent with experience. It is given by 



x' = /3 (x - vt) where /3 = (1 - -j)~^ 



y'= y 



z' = z 



t' = ^(t-^') 



Applying these equations we find that a length X2 — xi is shortened in 



V" 1/ 



the directions of motion by the factor (1 - — ) ^2. 



The paralellogram law for the addition of velocities is no longer 



U + V 



u + V but 



1 +UV 



These results would have very little interest to most of us if they 

 did no more than add very small corrections to our already compli- 

 cated system. The interest lies in the fact that they point to an 

 almost organic relation between space and time, so that we must 

 not consider space and time as being distinct concepts. 



242nd Meeting— May 25, 1920 



Dr. C. E. McClung, Professor of Zoology, University of Pennsyl- 

 vania — The Material Basis of Heredity. 



The lecturer, covering the chromosome theory of heredity, in- 

 troduced the principal facts, including the speaker's own well known 

 discoveries showing a correlation between the presence in germ cells 

 of particular chromosome masses and sex. (H. V. W.) 



