562 
NOTICES OF BIOGRAPHICAL MEMOIRS 
duced the four different types of structure in one and the same environ- 
ment. The four types of cells are then in an embryological sense poly- 
phyletic in origin. 
Therefore, vascular endothelium, erythrocytes and leucocytes, although 
all arise from mesenchyme, are really polyphyletic in origin; that is, each 
has a different mesenchymal anlage. To make the meaning absolutely 
clear, we may consider the origin of the liver and pancreas cells a parallel 
case, both arise from endoderm but each is formed by a distinctly 
different endodermal anlage, and if one of these two anlagen is de- 
stroyed the other is powerless to replace its product. 
A more complete account of this work, with a discussion of the Hter- 
ature bearing on the subject, appears in the September and November 
numbers of the American Journal of Anatomy. 
NOTICES OF BIOGRAPHICAL MEMOIRS 
The following biographical memoirs have been published by the Academy 
since the last notices of such memoirs appeared in the June number of the 
Proceedings. 
Henry Morton (1836-1902). By Edward L. Nichols. Biographical 
Memoirs of the National Academy, vol. 8, pp. 143-151. 
This Memoir consists in a description of the life-work of Henry Morton. It includes an 
estimate of his personality by Mr. Thomas A. Janvier quoted from the Morton Memorial 
Volume published by the Alumni Association of the Stevens Institute of Technology of 
which Mr. Morton was the first president. 
Peter Lesley (1819-1903). By W. W. Davis. Biographical Memoirs of 
the National Academy, vol. 8, pp. 155-240. 
This Memoir discusses the life-work of Peter Lesley, under the headings: Ancestry; Boy- 
hood; First Geological Work; Early Appalachian Study; Theology and Geology at Princeton; 
A Year Abroad; Preaching in Pennsylvania; Geological Work in Boston; Preaching in Mil- 
ton; Engagement and Marriage; The Lyman Family; Peter and Susan Lesley; Married Life 
in Milton; Lesley's Hobby, "Arkism;" Return to Pennsylvania and Geology; Anti-Slavery 
Opinions; Professional Work, its Pleasures and Pains; "Coal and its Topography;" Cata- 
strophic Views; Soil-Creep; Lesley as a Draftsman; Personal Opinions; The American Philo- 
sophical Society; The Iron Manufacturers' Guide; A Later Estimate of Rogers; Personal 
Items; Lowell Institute Lectures; Man's Origin and Destiny; Lesley as a Philologist; "Five 
Types of Earth Surface;" Two Years Abroad; More Personal Items; A Characteristic Inci- 
dent; Theoretical Views in Professional Reports; The University of Pennsylvania; Proof- 
reading; The "Second Survey;" The Drudgery of Survey Work; Distractions and Enter- 
tainments; The American Association; Trips to Europe; The Dictionary of Fossils; Sum- 
mary of Pennsylvania Geology; Recognition; Lesley in his Old Age. 
At the close the author of the Memoir presents a personal appreciation of Mr. Lesley. 
