PROF. HUXLEY ON THE AGAMIC REPRODUCTION 
214 
slender extremities of the eight oviducal and uterine tubes proceed,” and which are supposed 
There are no such bodies, that I can discover. 
to be ovaries, I am at a loss to divine. ) l 
In the latter part of the same citation, the existence of a histological difference between 
the contents of the pseudovarium and those of the ovarium is asserted. But there is 
assuredly nothing in the former to which the description can apply; and I re-affirm the 
impossibility of drawing any histological line of demarcation between the pseudova and 
the young true ova. : 
How any one who carefully studies the development of Aphis can arrive at the con- 
clusion that a portion of the germ-mass is taken into the body of the embryo Aphis, * like 
the remnant of the yelk of the chick," I know not ; and, for the reasons mentioned above, I 
even doubt if I clearly apprehend what is meant. Dr. Burnett (l. c. p. 73) assumes that 
what is intended by * portion of the germ-mass" is what I have termed the pseudovitellus. 
In that case the statement is erroneous ; for the pseudovitellus takes no share in the for- 
mation of the pseudovarium. If, on the other hand, the true rudiment of the pseud- 
ovarium is indicated, the statement in question is equally incorrect; for this is never out 
of the body, and hence can hardly be taken into it, nor can that out of which the so- 
called * oviducts” are produced be properly said to become * connected with them,” or to 
“aid in forming their filamentary extremities.” 
When the basis of a hypothesis is shown to be incorrect, the hypothesis itself is com- 
monly considered to be disposed of; but possibly in the present case it may be urged that, 
although the contents of the pseudovarium are wholly dissimilar “ to the germ-mass in 
in its state of minutest subdivision,” they are nevertheless so little changed that my 
criticism of the phrase is trivial. To this I reply that, whether the alteration be small or 
great, it is as great as that which occurs in the terminal cæca of a gland, or in a true 
ovarium, and that the tissue of the apical pseudovarian chamber is far more differentiated 
than the indifferent tissue which constitutes the youngest portion of an ordinary epithelium 
or epidermis. 
Whatever conclusions are based upon the resemblance of the tissue of the pseudovarium 
to that of the embryo, must therefore apply in equal or greater force to the tissues which 
I have just named ; and, unless reason can be shown to the contrary, whatever powers are 
possessed by the one, in virtue of this similarity, must be possessed in equal or greater 
degree by the other. 
But in this case what becomes of the hypothetical explanation of the asexual reproduc- 
tion of Aphis, under discussion ? 
The condition of such reproduction is, according to the hypothesis, the retention of 
* certain of the progeny of the primary impregnated germ-cell unchanged," « with so 
much of the spermatie force, inherited by the retained germ-cells from the parent-cell 9r 
germ-vesicle, as suffices to set on foot and maintain the same series of formative actions 
Mei which constituted the individual containing them." ; 
= for the sake of argument, that the amount of histological change 1» 
GE mass is unimportant. I am ready to suppose even, in accordance W* 
ypothesis, that its cells retain sufficient “spermatic force” (whatever that may be) 
