24 JOUENAL OF THE MiTCHELL SoCIETY [July 



The germ-plasm is early set apart in animals, but this is not 

 so in plants which develop new germ tissues each season. 

 Also it would seem more difficult for the environmental in- 

 fluences to penetrate the thicker envelope of body tissues in 

 animals, and to produce effects upon cells in more or less con- 

 stant environment. The body fluids surrounding these cells 

 and which constitute their environment are artificially main- 

 tained at fairly uniform pressure, temperature, composition, 

 and concentration. For these reasons it would seem to be 

 much easier for environmental factors such as temperature, 

 moisture, and light, to act upon the germ tissues of plants 

 than of animals. However this may be, it is much more than 

 probable that any generalization such as the inheritance of 

 acquired characters if found to be true for plants would also 

 be true for animals, although it is easily conceivable that 

 special animal characteristics might render the operation 

 more difficult of observation. 



Such a view appears at least to be near the truth. The 

 inheritance of environmental effects in some fashion has long 

 seemed to me a logical necessity. To assume that they are 

 not, would force the conclusion that all heritable variations 

 are represented in the germ-plasm, and, to carry the thing to 

 its ultimate end, there were l)undled up in the first organism 

 all the infinity of possibilities that have since appeared in 

 living things. Darwin, in liis later wi'itings, felt that the en- 

 vironment in some way acted upon the germ cells so as to call 

 forth variation, lait the cause of most variation was so dark 

 tliat lie fi-c<ineiitly referred to its as spontaneous. I take it, 

 however, tliat at the present time no scientific man will under- 

 take to maintain spontaneity of any kind and by the word 

 merely means that the cause is unknown. 



Tlicrefore, so far as I can see, we are shut up to one or 

 the other of these conclusions, either new characters, which 

 can be transmitted and summed up in heredity, are called 

 forth by the environment, or all past, present, and future 

 variations were present in that primordial germ cell and sub- 

 sequent variation has been a process of release by the drop- 



