1902.] OLIVER— BLINDNESS FROM MALFORMATION OF SKULL. 171 



volved become the ocular end organs. In this type the most bizarre 

 motor ophthahiiic signs are commingled in complicated yet definitely 

 determinate interrelationships. On the contrary, the further back 

 the coarse osseous changes are found, the greater become the sen- 

 sory deficiencies of the visual apparatus and the better preserved 

 remain the organs of vision and their contiguous parts. 



In the anterior types the main basal cause of the condition may 

 be summed as a series of asymmetries of basilar structures, with 

 coarse anomalies in the various portions of the underlying sphenoi- 

 dal and contiguous bones. 



In the posterior types histological examination reveals cortex and 

 nuclear changes in the posterior part of the sensory portions of the 

 visual apparatus. In some such individuals the cellular elements 

 may have attained a good size, and may have been able to function 

 most excellently during early postnatal life. This can be under- 

 stood when it is realized that nearly ninety per cent, of the gross 

 volume of the brain mass is obtained during the first stage of post- 

 natal existence ; later, the association fibres and the neural cells 

 continue to be the main factors of growth. This development, of 

 course, exerts its influence upon the formative processes taking place 

 in the osseous cranium. 



In the majority of cases of these types there is a true tissue- 

 sclerosis. 



In deformation of the cranium occurring at a very early antenatal 

 stage, the visual apparatus is more liable to become affected than 

 any of the other special sense organs. On the contrary, morbific 

 causes which affect the same apparatus during the later stages of 

 development of the skull and its contents are not so apt to affect 

 the organs of vision. It may be also of interest to state that the 

 sensory portion of the visual apparatus being developed much earlier 

 than the motor, and not possessing so many separations and ramifi- 

 cations in midbrain, is better able to withstand coarse pathological 

 changes than the latter. Statistics and personal observations, how- 

 ever, have determined that the great majority of congenitally blind 

 subjects possess malformations of the skull and its appendicular 

 elements. 



Far different are the grosser forms of more generalized cranial 

 deformation, such as the two great classes, microcephales and ma- 

 crocephales. Coarser disturbances of sensation, grosser peculiarities 

 of motion, and increased degrees of trophic condition affect other 



