Factors general to changing health care and expectations and others specific to mental health would appear to have led to the increase in rates of admissions observed in the modern period.

Maturation of respiration in prematures and young infants. Neuropadiatriie 3: 294-304 (1972). Changes in respiratory patterns were studied in prematures from 30 wks. oonceptional age to 8 mons. past term and in full term infants between 40 wks. conceptional age (and 8 tnons. past term. Regular respiration was found to increase greatly after 36 wks. concepuional >aige, while very little periodic breathing or lapnea were seen after this age. Irregular respiration accounted foir 5O°/o of each 2-3 hr. record, until 8 months past term, when it was less. In addition, the maturaioional increase in regular respiration was concurrent with increases in the simultaneous presence of other indicators of nervous system inhibition, specifically, the absence of eye and body movements.It is argued that these maturational changes could not be adequately explained by current theories. A model of the development of respiratory control is proposed, based on the concept that the neuronal complexity of interaction at each brain level increases at the same time that the hierarchical locus of control moves upward and the interaction between all brain levels becomes more complex.