July, 1891 . 
ANIMAL PEDIGREES. 
145 
ANIMAL PEDIGBEES.* 
BY A. MILNES MARSHALL, M.A., M.D., D.SC., F.R.S., 
BEYER PROFESSOR OF ZOOLOGY IN OWENS COLLEGE, MANCHESTER. 
(Continued from page 129.) 
We must now turn to another side of the question. 
Although it is undoubtedly true that development is to be 
regarded as a recapitulation of ancestral phases, and that the 
embryonic history of an animal presents to us a record of the 
race history ; yet it is also an undoubted fact, recognised by 
all writers on embryology, that the record so obtained is 
neither a complete nor a straightforward one. 
It is indeed a history, but a history of which entire chapters 
are lost, while in those that remain many pages are misplaced 
and others are so blurred as to be illegible ; words, sentences, 
or entire paragraphs are omitted, and, worse still, alterations 
or spurious additions have been freely introduced by later 
hands, and at times so cunningly as to defy detection. 
Very slight consideration will show that development 
cannot in all cases be strictly a recapitulation of ancestral 
stages. It is well known that closely allied animals may 
differ markedly in their mode of development. The common 
frog is at first a tadpole, breathing by gills, a stage which is 
entirely omitted by the West Indian Hylodes. A crayfish, a 
lobster, and a prawn are allied animals, yet they leave the 
egg in totally different forms. Some developmental stages, 
as the pupa condition of insects, or the stage in the develop¬ 
ment of a dogfish in which the oesophagus is imperforate, 
cannot possibly be ancestral stages. Or again, a chick embryo 
* Owens College, 
June 15th, 1891. 
To the Editor of the “ Midland Naturalist.” 
Sir,—Kindly allow me to correct an error in the part of my paper 
on “ Animal Pedigrees ” that appeared in the June number of the 
“ Midland Naturalist.” 
I quoted, as examples of rudiments, the silent letters in certain 
words ; and amongst these is given, on page 124, the letter g of the word 
“foreign.” The word I wrote, or intended to write, was “ reign,” in 
which the g, now mute and rudimentary, is traceable by direct descent 
from the g of the Latin regnum. 
The g of “ foreign ” is not a rudiment: how it got into the word I 
must leave the etymologists to explain, but it is most certainly an 
acquired and not an ancestral character. 
It is a good illustration of the difficulties with which a morphologist 
is constantly confronted that in two words so similar in appearance 
the exceptional letter should have such totally different histories. 
Yours, &c., 
A. Milnes Marshall. 
