THE CELL AND SOME OF ITS CON- 

 STITUENT STRUCTURES.^ 



FROM old time it has been one of the highest aims 

 of Philosophy to penetrate the veil which obscures 

 the mysteries of life and of organisation, and the concen- 

 tration of such an immense amount of attention on the 

 minute details of cell structure during the past few years 

 is the outcome of a conviction that this is one of the most 

 favourable means of attacking the problems we seek to 

 solve. But so vast a mass of knowledge has been acquired 

 that perhaps we run some danger of missing the goal amid 

 the maze of paths which have been opened up towards it. 

 And thus it may not be altogether amiss to stand still for 

 awhile and try to take stock of our position, to criticise the 

 various conflicting opinions, and to test as far as may be, 

 the foundations on which they rest. And one of the first 

 facts to which it is necessary to be warily alive, in inquiries 

 such as these, is that the vast majority of the observations 

 on which we rely have been made on the dead cell. That 

 is, we are trying to form a conception of what goes 

 on in living protoplasm from results gained by a study of 

 structures preserved in a dead substance which is certainly 

 no longer protoplasm. We assume, but we ought to be con- 

 stantly testing the validity of our assumption, that in what 

 we call well- fixed material, at any rate the grosser structural 

 arrangements of the protoplasm as it existed in the living 

 condition are preserved to us. But the difficulty lies ex- 

 actly in determining our criterion of proper fixation, and a 

 neglect of this precaution may render utterly valueless even 

 an accurate description of what an observer sees, unless he 

 can satisfy his readers that he is not, as a matter of fact, 

 merely describing artefacts, appearances artificially pro- 

 duced during the process of killing. Indeed, one often 

 hears this ^/rzbrz objection urged against cytological work 



^ Read before a combined meeting of Sections D and K of the 

 British Association, 22nd September, 1896. 



