THE CELL-THEORY 249 



than none at all, but is a necessary forerunner of, and preparation for, 

 the true one. As Schwann himself well expresses it : 



" An hypothesis is -never hurtful, so long as one bears in mind the 

 amount of its probability, and the grounds upon which it is formed. 

 It is not only advantageous, but necessary to science, that when a 

 certain cycle of phenomena have been ascertained by observation, 

 some provisional explanation should be devised as closely as possible 

 in accordance with them ; even though there be a risk of upsetting 

 this explanation by further investigation ; for it is only in this way 

 that one can rationally be led to new discoveries, which may either 

 confirm or refute it." (p. 221.) 



The value of an hypothesis may, in fact, be said to be twofold — 

 to the original investigator, its worth consists more in what it suggests 

 than in what it teaches ; let it be enunciated with perspicuity, so that 

 its logical consequences may be clearly deduced, and made the base 

 of definite questions to nature — questions to which she must answer 

 yes or no — and of its absolute truth or falsehood, he recks little : for 

 the mass of men, again, who can afford no time for original research, 

 and for the worker himself, so far as respects subjects with which he 

 is not immediately occupied, some system of artificial memory is 

 absolutely necessary. This want is supplied by some " appropriate 

 conception " which, as Dr. Whewell would say, " colligates " the facts — 

 ties them up in bundles ready to hand — by some hypothesis, in short. 

 Doubtless the truer a theory is, — the more "appropriate " the colligating 

 ■conception, — the better will it serve its mnemonic purpose, but its 

 absolute truth is neither necessary to its usefulness, nor indeed in any 

 way cognizable by the human faculties. Now it appears to us that 

 -Schwann and Schleiden have performed precisely this service to the 

 biological sciences. At a time when the researches of innumerable 

 guideless investigators, called into existence by the tempting facilities 

 offered by the improvement of microscopes, threatened to swamp 

 science in minutis, and to render the noble calling of the physiologist 

 identical with that of the 'putter-up' of"p reparations, they stepped 

 forward with the cell-theory as a colligation of the facts. To the 

 investigator, they afforded a clear basis and starting-point for his 

 inquiries ; for the student, they grouped together immense masses of 

 details in a clear and perspicuous manner. Let us not be ungrateful 

 for what they brought. If not absolutely true, it was the truest thing 

 that had been done in biology for half a century. 



But who seeks for absolute truth ? Flattering as they were to our 

 vanity, we fear it must be confessed that the days of the high a priori 

 road are over. Men of science have given up the attempt to soar 



