THE EXPERIMENTAL PRODUCTION OF AN INTERNAL HYDROCEPHALUS. 435 



As the enlargement of the head is the most striking abnormality to be made 

 out in the kitten during life, a description of this anatomical change will be included. 

 The first noticeable development, as already mentioned, is the alteration in the 

 suture lines. The opening or enlargement of a suture is usually to be demon- 

 strated by gentle palpation; a definite increase in the cranial vault has been noted 

 with certainty on gross inspection only after the fourth day, though before this 

 time palpation gave good assurance of this increase. The enlargement of the 

 head was usually made obvious by alteration in the angulations; this was due 

 to the lack of associated expansion in the base of the skull. One of the first read- 

 justments to this increase in size of the cranial cavity was the elevation of the line 

 of the forehead so that the profile rose abruptly from the line of the nose. This is 

 shown in several figures (No. 11, from a kitten during life, and also Nos. 6 and 9). 

 In the normal kitten the line of the skull in profile slopes backward in a very 

 gentle angle of ascent, while the kitten with the intraspinous lampblack shows an 

 increasingly abrupt rise to the forehead (fig. 9). In the course of about 2 weeks 

 the enlargement of the vault is so great that on front view the forehead seems to 

 tower above the orbital ridge (figs. 5 and 6). 



This increase in size of the vault with marked elevation of the forehead is 

 associated with other equally characteristic features. The elevation of the vault 

 proceeds in these kittens so rapidly that the orbital ridge gradually seems dis- 

 placed backward or obliterated (figs. 5 and 11). As the growth of the base of the 

 skull proceeds as normally in these kittens, the increased intracranial tension 

 continues to pull upward the restraining portions of the base. Laterally, however, 

 over the ears, the whole vault bulges markedly also and overhangs more prominently 

 the bony canal (figs. 7 and 9). Here the bulging is more or less opposed to the 

 retraction of the bony orbital ridge. The result of these forces is the rounding up 

 of the whole cranial vault and to a lesser extent of the base of the skull, with an 

 increase in the transverse diameter and a relatively smaller increase in the sagittal. 

 This apparent rounding-up is shown in figures 10, 13, and 17. 



These alterations in the shape and size of the cranium have other readjustments 

 of the general appearance of the animal associated with them. Most striking of 

 all is the general appearance of bulging of the whole head due -to an increased con- 

 vexity between ears and between occiput and glabella (cf. figs. 7 and 11). In the 

 extreme cases the whole head may resemble the typical " Turmschadel " noticed 

 clinically in man. The ears seem in consequence to be placed at relatively low 

 level in the skull on account of the fact that the enlargement has been wholly above 

 the base (figs. 6 and 11). 



Quite similarly caused is the pulling upward of the skin from the face and 

 lower part of the head by the enlargement of the vault. This results in the typical 

 white line of sclera showing above the iris and in the obscuring of the lower half 

 of the pupil by the lower lid. With the obliteration of the orbital ridge, the sclera 

 beneath the retracted upper lid appears as a wide crescent, best to be seen from 

 above because of the retracted orbital ridge. This can be made out in figures 7 

 and 11. 



