56 ON THE AGAMIC REPRODUCTION AND MORPHOLOGY OF APHIS 
tion, the reductio ad absurdum by simple arithmetic, of the so-called 
explanation, appears to me to be sufficiently obvious. 
For the sake of argument, however, I am willing still to suppose 
for a moment that agamogenesis does take place in consequence of 
the retention of a “spermatic force.” But I must ask, how does this 
phrase constitute an explanation of the phenomena? Nothing is 
more common than the misuse of the word “force” on the part of 
those who are more versed in the phraseology, than trained in the 
severe methods, of physical science. The impatient inquirer every 
now and then calls in the aid of molecular force, or chemical force, or 
magnetic force, or od-force, to account for the existence of a mass 
of phenomena which will not arrange themselves under any of his 
established categories—forgetting that a “force,” the conditions of 
whose operation (that is, whose laws) are undetermined, is but a 
scientific idol, at once empty and mischievous,—empty, because it is 
but a phrase without real meaning ; mischievous, because it acts as 
an intellectual opiate, confusedly satisfying many minds and ob- 
structing the progress of inquiry into the real laws of the phenomena. 
If we show that a fact is a case of a law, we explain that fact; but 
explanation by reference to an undefined “force,” of questionable 
existence, is simply ‘ignorance writ large.’ 
Now, how does the hypothesis fulfil the indispensable conditions 
of a genuine explanation? In the first place, what proof is there of 
the existence of such a force as ‘spermatic force’? All that we know 
is, that an ordinary ovum will not undergo those changes which con- 
stitute development without the contact of the spermatozoon. Hence 
it is concluded that some force contained in the spermatozoon is the 
efficient cause of all these changes. But what would be thought of 
the artillerist who should imagine he had explained the propulsion 
of a bullet by saying it was ‘trigger force’? Or, to take an illustra- 
tion from phenomena of a like order to those under discussion: a 
seed will not grow unless it is exposed to a certain amount of warmth 
and moisture ; but have I explained the growth by saying that it is 
the effect of ‘heat and moisture force’ which becomes diffused 
through the seed? 
The very existence of this “spermatic force,” then, is a gratuitous 
assumption; and if we seek for its laws of action, we find but two 
stated : first, that it becomes weakened by the successive divisions of 
the germ-cell ; second, that “the force is exhausted in proportion to. 
the complexity and living powers of the organism developed from the 
primary germ-cell and germ-mass.” 
I have shown to what singular consequences the first assumption 
