A CRITICISM OF THE CELL-THEORY. 1738 
from experience, for not long since I was much puzzled by 
such a reticulum, and had I been less cautious I should have 
published, as a great morphological discovery, statements which 
rested on a wholly insufficient basis of experience. The subject 
requires further investigation, and the most that one can say 
now is, that it is possible that Mr. Sedgwick, good observer as 
he is, may have been mistaken. And he will pardon my 
observing that the things which he states are not “ facts.” 
They are his own inferences from his own individual observa- 
tions, and will require very abundant confirmation before they 
can take rank as what we agree to regard as “ facts.”” All the 
“ facts ” we have at present, i. e. the accumulated observations 
of hundreds of highly-trained and able observers, are funda- 
mentally opposed to any such account of protoplasmic growth 
apart from nuclear formation as Mr. Sedgwick gives us. But 
there is another way of looking at it, namely, that he has only 
overstated his case, and that the growth of the tissues in 
question resembles the apparent creeping motion of the plas- 
modia of the Myxomycetes. That this may be the case is 
supported by a study of Mr. Assheton’s receut account of the 
growth of the mesoblast and of the inner layer of the epiblast 
in the embryo of the rabbit. It presents no theoretical diffi- 
culties, but it should be remarked that Mr. Assheton figures 
numerous nuclei at the very edge of the growing part of his 
reticula, which is consonant with what we know of proto- 
plasmic growth in other cases, but not with Mr. Sedgwick’s 
account. 
But if Mr. Sedgwick can prove that the reticulum is there 
and that it grows and spreads far from the nuclei which sub- 
sequently migrate into it, he must not suppose, as he is 
apparently so ready to assume, that the inveterate prejudice 
of morphologists will prevent their accepting his conclusions 
because of their theoretical difficulties. If his case is proved, 
it will be accepted, but he must prove it up to the hilt. 
And if he does prove it, what then? It will be an isolated 
case, of secondary significance: merely another addition to 
our experience of the very various phenomena displayed in 
