960 



TERATOLOGY. 



Internal hydrocephalus has always a pre- 

 judicial influence upon the condition of the 

 rest of the body, principally upon its nutrition 

 and upon the osseous system, which it pre- 

 disposes to emollition. It has a very great 

 influence on the bones of the skull. Its effects 

 are : 



a. A large expansion of the skull, whilst 

 the face preserves its common shape, and is 

 in great disproportion to the enormous cir- 

 cumference of the skull. This disproportion 

 is the most significant symptom of hydroce- 

 phalus, and distinguishes it from simple am- 

 plification of the head. 



b. A protuberance of the frontal tubero- 

 sities, which is to be considered as an arrest 

 at an early period of developement, occasion- 

 ing an enormous augmentation of the facial 

 angle, which greatly exceeds a right angle. 



c. A pushing downwards of the orbital 

 parts of the frontal bone, which makes the 

 superior orbital margins to disappear totally, 

 and to form a protuberance with the frontal 

 part of the frontal bone. The eyes thence 

 acquire a strange direction, their axes being 

 turned upwards. 



d. A-symmetry of the hydrocephalous 

 head, which is always more or less oblique. 

 This is the effect of the unequal expansion of 

 the brain. To this may also be ascribed the 

 strange form which the skull acquires when 

 it is regularly extended and developed on its 

 fore and lateral parts, whilst the occiput has 

 a very singular prominence. Such a form 

 is, without doubt, occasioned by a regular 

 expansion of both the hemispheres of the 

 brain up- and sidewards, whilst their posterior 

 lobes and the cerebellum have preserved their 

 regular form. The parietal bones are thereby 

 expanded and augmented in circumference, 

 whilst the occipital bone, not participating in 

 the expansion, is disproportioned to the rest 

 of the skull. The parietal bones are removed 

 from it, so that, during the primitive ossifica- 

 tion, an interval is formed, which is after- 

 wards filled up with Wormian ossicles. 



Not less singular is the form of the head 

 and skull, when, probably on account of the 

 position of the head in the womb (as is the 

 case in a partus pedibus prceviis), the pressure 

 of the fluid has been exercised principally 

 downwards, so as to extend chiefly the lateral 

 parts of the head. 



<?. An abnormal disposition of the cranial 

 bones. The fontanellse acquire, in the first 

 instance, a very large dimension, and some 

 parts of the cranial bones remain cartila- 

 ginous, which parts are, in a more advanced 

 period, filled up with Wormian ossicles. 

 Baillie asserts, that sometimes the already 

 formed sutures are opened by the serum 

 exuded in hydrocephalus internus. In other 

 cases, the want of closure of the sutures is to 

 be imputed to a too great thinness of the 

 bones. 



2. Hydrocephalus externus is by somefMonro, 

 Wrisberg, Kartell) erroneously considered as 

 the result of hydrocephalus internus, followed 

 by laceration of the cerebral hemispheres. 



It is proved, by a great many observations, 

 that such a laceration occurs very seldom. 

 The fluid is, in most cases of hydrocephalus 

 externus, exuded on the surface of the brain. 

 This may be the consequence of an arrest of 

 developement, as I observed in a cyclopic lamb, 

 but it may also be produced by inflamma- 

 tion. The serum is accumulated between the 

 dura mater and the skull, or between the two 

 layers of the arachnoid membrane, but in 

 most cases its situation is between the dura 

 mater and the arachnoid membrane. In all 

 these cases the brain is strongly compressed, 

 shrunken, and hard (Kaltschmidt). Dullness 

 and somnolence are, according to Frank, the 

 consequences of hydrocephalus externus, and 

 convulsive affections those of hydrocephalus 

 internus. 



V. AcephaU, or Foetus without a Head. 



When we observe the foetus in its first 

 periods of developement, the head is not yet 

 clearly distinct from the trunk. From the 

 third :o the fifth week of gestation, the head, 

 not previously discernible, grows so rapidly, 

 that it has in the fourth week acquired the 

 same volume as the trunk. Now the de- 

 velopement of the foetus is sometimes arrested 

 at that early stage when the head is not yet 

 distinguishable ; the result of such an arrest 

 must manifestly be an acephalus. This de- 

 nomination is, again, as erroneous as many 

 others ; for not only the head, but many 

 other parts, are wanting. The question re- 

 mains whether a more appropriate name could 

 be given. Gurlt tried to do so, but, I fear, 

 not with good success. He calls the lowest 

 form of acephali amorph-us globosus, which is a 

 true contradictio in adjecto. I think it there- 

 fore proper to preserve the old name of 

 acephali, to which I refer, as has been done 

 by Tiedemann and G. Vrolik, nine types, for 

 which I think it not necessary to give special 

 names. 



First Type. AcephaU in the form of a 

 rounded mass, without any indication of extre- 

 mities. Examples have been given by G. 

 Vrolik, Bland, and W. Vrolik, all of twins. 

 The rounded mass is covered with the skin ; it 

 contains an intestinal fold, and receives the 

 insertion of the umbilical cord. In general 

 there is found in it the rudimental indication 

 of vertebra? and of spinal medulla. 



Second Type. Acephali in the form of 

 a rounded mass, with indication of feet. The 

 chief observations of this form have been 

 given by G. Vrolik and Clarke, in cases of 

 twins. They have an umbilical cord, rudi- 

 mental external genital parts, and an anal 

 orifice, with an imperfect abdominal cavity, in 

 which are contained an intestinal loop formed 

 by a colon and caecum, and kidneys. Conse- 

 quently all the thoracic viscera, the liver, the 

 spleen, pancreas, stomach, and the small in- 

 testines, are wanting; but there is a rudiment 

 of a nervous system, a tolerably complete 

 right inferior extremity, a pelvis, and a left 

 separate foot, without femur and crus. (Figs. 

 GIG, 617.) 



