What did william harvey's observations and experiments show

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.        

texas governor sam houston opposed secession, but was unable to prevent it. in this speech, given prior to lincoln's election, he presents the argument that slavery would be safer within the united states than outside of it. it was a prescient argument, and one held by several other southern leaders.

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