Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Dashboard
Publications
Account settings

Search…

Primary site navigation

Search

Logged in as:

Dashboard
Publications
Account settings

Search PMC Full-Text Archive

Journal List
User Guide

As a library, NLM provides access to scientific literature. Inclusion in an NLM database does not imply endorsement of, or agreement with, the contents by NLM or the National Institutes of Health.
Learn more: PMC Disclaimer | PMC Copyright Notice

. 1926 Jul;106(1):47–57.

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

Current Topics

Editor: J N Cruickshank

This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License, which permits non-commercial use and redistribution provided that the original author and source are credited.

PMC Copyright notice

PMCID: PMC5961989 PMID: 30437992

Full text

47
48
49
50
51
…
57
Next

ACTIONS

PDF (2.5 MB)

RESOURCES

Cite

Download .nbib .nbib
Format:

Add to Collections

Create a new collection

Add to an existing collection

Name your collection *

Choose a collection

Unable to load your collection due to an error
Please try again

Follow NCBI

NCBI on X (formerly known as Twitter) NCBI on Facebook NCBI on LinkedIn NCBI on GitHub NCBI RSS feed

Connect with NLM

NLM on X (formerly known as Twitter) NLM on Facebook NLM on YouTube

National Library of Medicine
8600 Rockville Pike
Bethesda, MD 20894

Web Policies
FOIA
HHS Vulnerability Disclosure

Help
Accessibility
Careers

NLM
NIH
HHS
USA.gov