Working hypotheses tentative

We have drawn the following tentative conclusions as a working hypothesis for future studies, (i) PGD2 and PGE2 are endogenous sleep and wake substances,... 

Originally advanced as a tentative working hypothesis, the demonstration within the next few years that additional members of the vitamin B complex are prosthetic groups of enzymes, together with the apparent vindication of the thesis in the case of additional pharmacological agents (Green, 1946), led to a situation where the hypothesis assumed, in many circles, the transcendental quality of a natural law. 

The shrewd guess, the fertile hypothesis, the courageous leap to a tentative conclusion—these are the most valuable coin of the thinker at work whatever his line of work. 

It had been inferred from the earlier work by rather incomplete evidence that somehow the capacity to make HCN is primarily dependent on arc conditions no matter how far removed the injection point is from the arc unit itself. A further objective of this experiment was therefore systematically to check this tentative conclusion by careful control and variation of the injection point on a long reactor. From the standpoint of the titration hypothesis, if the arc unit conditions are indeed controlling,... 

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