GASTRULATION IN BIRDS. 
145 
Gastrulation in Birds. 
By 
Richard Asslictoii, lil.A., 
Lecturer on Physiology in Guy's Hospital, University of London. 
In the twentieth volume of the ‘Journal of Morphology’ 
a p:iper by Mr. J. T. Patterson uppeared during the year 
1909 under the title, “ Gastrulation in the Pigeon’s Egg : 
A Morphological and Experimental Study,” a preliminary 
notice of which was published in 1907 in the ‘ Biological 
Bulletin,’ vol. xiii. 
In these papers the author gave an entirely novel account 
of the process of gastrulation in a bird, which account, if 
free from error, described an interesting, albeit perplexing, 
phenomenon. 
The paper is fully illustrated by photographs and diagrams, 
and has the appearance of being a careful piece of work, 
and it has been used by Professor Frank R. Lillie as the 
basis of his description of the early stages of bird develop- 
ment in his recent book, ‘The Development of the Chick.’ 
Professor Lillie writes, on page 52, that he “ has had the 
opportunity of following the work step by step, and is 
convinced of its accuracy.” 
The paper describes so unusual a process that, in spite 
of this testimony, it courts a rather close examination. 
Moreover, if correct the matter should be relieved of all 
suspicion, because it Avould in that case be a highly important 
contribution to the embryology of birds. 
Since it seems to me that the description given by 
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