Maddox, on Parasites of the Common Haddock. 95 
Whether these ovoid globular bodies should be regarded as 
u sporularia,” in which “ sporulse ” are developed, using these 
terms, as Von Siebold, to mean germs, which are not only de- 
void of the ordinary constituents of an ovum, as vitelline mem- 
brane, yelk, germinal vesicle, and the so-called germinal 
spot, but in which the further development of the germ-body is 
not preceded by those conditions, (I mean that of “ impregna- 
tion ” by means of special seminal matter produced in a 
testis,) which are essential to the development of true ova de- 
veloped within an ovarium, I cannot decide. In a paper 
translated by Mr. Dallas, in f Annals and Magazine of 
Nat. Hist.,’ No. cii, 1866, there occurs this passage from 
Professor R. Leuckart, in speaking of the trematode worms : 
“ There are trematoda, the embryos of which even attain sexual 
maturity in their Rhabditist-/orm, and only become 'parasitic 
again in their progeny — trematoda, consequently the history 
of which presents us with no simple alternation of the con- 
ditions of life, but with an alternate sequence of free and 
parasitic generations. And, what is more wonderful, both 
these generations are sexually developed ,both are produced from 
ova. There, therefore, we have nothing to do with an ordi- 
nary alternation of generations such as occurs, for example, 
in the Distomese, but with a process hitherto almost unheard 
of in the animal kingdom, and which calls for our considera- 
tion the more, because we are accustomed to regard the 
sexual development of an animal not merely as the sign of 
its perfect maturity, but also as the criterion of specific indi- 
viduality.” 
The view of self-impregnation has been held by some, but 
Dr. Cobbold thinks erroneously, for he says — “ Having 
found two of the flukes (. Distoma conjunctum, Cobbold) 
sexually combined, a fact of great significance in relation to 
the probably erroneous notion entertained by some, that the 
hermaphrodite flukes are capable of self-impregnation ; ” 
still, as this only proves the one form of congress, to my own 
mind it does not present any serious difficulty, seeing that 
almost every day fresh ideas, through increased knowledge, 
are adding to the peculiarities of the “ ways and means ” by 
which the deviations from the ordinary paths of develop- 
ment are effected, to yet carry forward the one grand end — 
the continuation of the species. Indeed, to me it almost 
seems less extraordinary that in the hermaphrodite, which is 
itself a deviation, we should have the power of direct develop- 
ment up to at least a certain form, if not to the full nature 
of the highest phase of the creature’s existence ; thus might 
it not be that the type for self-impregnation, allowing it to 
