8 
PRELIMINARY REMARKS. 
On the fifth of October, 1850, this memoir was read before the Boston Society of 
Natural History,* and referred to the publishing committee, which reported in favor 
of publication in its Journal whenever the funds of the Society could meet the ex- 
penses required by the illustrations. 
i 
At the suggestion of several of my New England friends, I withdrew the memoir 
upon my leaving the North, hoping to find a speedier way of bringing it before the 
public. But circumstances out of my control have occasioned a delay of three years, 
during which period several works of embryology have passed through the press, which, 
although not treating of the same special subject, would have induced me to modify 
some of the paragraphs of my original memoir, had I not desired to preserve the form 
in which it was originally written. 
A few paragraphs, however, have been added to the chapter on the fecundation, and 
to the conclusion, in which I have felt it my duty to refate an assertion, since made, 
against the views I hold in regard to the systematic position of Planarians. 
The first part of these Researches was originally published in the second volume, 
of the new series, of the “Journal of the Academy of Natural Sciences of 
Philadelphia.” 
C. G. 
Washington^ Nov. 1, 1853. 
* Proc. Bost. Soc. Nat. Hist. iii. 1850, 348. 
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