W. p. MCNULTY 
833 
deserve more detailed pathologic examination 
and correlation with functional tests. 
Sudden unexpected death in infancy 
"Crib death" is a frequent diagnosis in hu- 
man infants dying in the second through the 
twelfth month of life. This is the circumstance 
which in the past has been called "status thy- 
molyphaticus," "smothering in the bed clothes," 
or "early interstitial pneumonia." Typically a 
child in outward good health in the evening is 
found dead in the morning. No consistent ana- 
tomical changes are found at autopsy, and 
bacteriologic and virologic studies of lungs and 
blood have been unrewarding. The condition 
remains a tragic enigma. 
We have made this diagnosis in 4 infant rhe- 
sus monkeys for obvious reasons on clinical 
rather than anatomical grounds. Since by defini- 
tion the "illness" has no known natural history 
and death comes without warning, the occur- 
rence of this condition does not constitute a 
model in the usual sense. 
Hyaline membrane disease 
This affliction is poorly named, because if 
death occurs very early the characteristic eosin- 
ophilic precipitates in respiratory and terminal 
bronchioles may be difficult to find. The diagno- 
sis may usually be made with confidence, how- 
ever, from a characteristic pattern of dilatation 
of respiratory bronchioles and collapse of al- 
veoli.3 Twice this has been tentatively diagnosed 
in rhesus babies; the pattern was present but 
not the membranes (Fig. 8). 
In human infants, immaturity and asphyxia 
appear to be predisposing factors, leading to a 
failure in maintenance of the concentrations of 
lipid surfactant in alveoli necessary for aera- 
tion.* These factors might be easily manipulated 
experimentally. 
Pneumoconioses 
Deposits of particulate foreign material are 
common in lungs. Kaolin (aluminum silicate) 
has been inadvertently put in the lungs during 
attempted gastric intubation, resulting in a 
granulomatous pneumonia. The pigments of 
mite infestation have already been mentioned. 
Unidentified brown and black pigments, some- 
times crystalline and polarizing, appear often 
in alveolar macrophages and in interstitial tis- 
sue and regional lymph nodes. Presumably some 
of this is anthracotic pigment from suburban 
air; some may be from dusts and aerosols pe- 
culiar to colony environments. In no case has 
this deposition been associated with emphysema, 
fibrosis, or pulmonary arteriosclerosis (except 
in the case of mites) and we have not tried to 
identify the substances. 
Immune diseases 
Some of the least understood human pulmo- 
nary diseases are loosely grouped as inappro- 
priate responses of the immune system, such as 
bronchial asthma, Goodpasture's syndrome, 
rheumatic pneumonitis, and progressive pul- 
monary sclerosis (Hamman-Rich disease). We 
have not seen, or at least recognized, changes in 
monkey lungs suggestive of these conditions. 
Neoplasms 
Although some major factors in the etiology 
of human lung cancer are well known (cigarette 
smoking, radiation, asbestos) possible other 
contributing factors, such as occult viruses and 
inheritance, are not. With the exception of a 
Figure 8. — Lung of a female rhesus infant dying with 
respiratory distress in first day of life. The terminal 
bronchioles are dilated, alveoli are collapsed. Hyaline 
membranes are not present. H & E, 50x. 
