ON THE AGAMIC REPRODUCTION AND MORPHOLOGY OF APHIS 53. 
the cases of the development of an embryo from a parent that has 
not itself been impregnated. The cause is the same in kind, though 
not in degree, and every successive generation, or series of spontaneous 
fissions, of the primary impregnated germ-cell, must weaken the 
spermatic force transmitted to such successive generations of cells. 
“The force is exhausted in proportion to the complexity and 
living powers of the organism developed from the primary germ-cell 
and germ-mass.”’—J/dzd. pp. 72, 73. 
These statements are repeated in the recently published second 
edition of Professor Owen’s “Lectures on the Invertebrata.” 
The paragraphs I have cited contain two kinds of propositions— 
assertions with respect to matters of fact, and deductions from those 
assertions. The former are, according to my observations, incorrect ; 
and, as I conceive, the latter are unfounded. 
As regards the first citation, for instance, the contents of the 
apical chambers of the pseudovaria are zof by any means identical 
with those “resulting from the final subdivision of germ-cells retained 
unchanged,” as the most cursory comparison of the two structures 
will show. 
In the second citation it is affirmed that the germs are perceptible 
in the embryo before any organs are formed for their reception. 
This, again, is an error if my observations are correct. The absence 
of figures, and the too vague and general character of the descriptions 
in Professor Owen’s work, render it very difficult to understand what 
he really has seen; but I imagine that he has taken the substance 
which constitutes the rudiment of the whole pseudovarium, and which 
becomes differentiated partly into pseudova, partly into the walls of 
the organ, for a mass of germs. What is meant by “those two bodies 
from which the slender extremities of the eight oviducal and uterine 
tubes procéed,” and which are supposed to be ovaries, I am at a loss 
to divine. There are no such bodies, that I can discover. 
In the latter part of the same citation, the existence of a histo- 
logical 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 Aphzs can 
arrive at the conclusion that a portion of the germ-mass is taken into 
the body of the embryo Apfzs, “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 (4 ¢ p. 73) 
