958 



TERATOLOGY. 



under the form of cauda equina; to the larger 

 sheath formed there by the dura mater ; and 

 to the very limited tendency which the osse- 

 ous nuclei of the lumbar and sacral vertebra 

 show to unite themselves into an arc, which 

 therefore remains always open at the inferior 

 part of the sacrum. Although it occurs some- 

 times alone, this sort of fissure is generally 

 accompanied with dropsy of the spinal medulla 

 (hydrorachis}, that is to say, with a sac of a red- 

 dish-violet colour, in which fluctuation is easily 

 discerned. Its external covering is sometimes 

 formed by the skin, and then it has the usual 

 colour of the body ; the skin, however, does 

 not in most cases cover the whole surface of 

 the tumour, but ceases at its circumference, 

 and the rest of its surface is only covered with 

 the dura mater. When the child lives, the 

 dura mater becomes, after some time, thicker, 

 harder, and more solid. When the tumour 

 is covered with the skin, the dura mater is to 

 be found under it. These membranes become 

 often so thick, and so intimately united to- 

 gether, that it is nearly impossible to separate 

 them from each other. The serum contained 

 in the tumour is of a very variable quality, 

 principally composed of albumen, mucus, ge- 

 latin, and muriate of soda (Bostock). It is 

 effused between the pia mater and the arach- 

 noidea, or between this and the dura mater, 

 or in the primitive canal of the spinal me- 

 dulla. If this canal remains open, the hydro- 

 rachis is in general accompanied with hydro- 

 cephalus interims. Sometimes these sacs are 

 found on more than one spot of the spinal 

 medulla, or divided into two by a septum. 

 The size of the sac varies, and the complication 

 with hydrocephalus is very dangerous. If this 

 is the case, the artificial opening of the sac has 

 a very injurious effect. Convulsions and exu- 

 dative inflammation are in most of the cases 

 excited by it. In some very rare cases the 

 operation was attended with success. Sir 

 Astley Cooper healed hydrorachis by reiterated 

 puncturing with a thin needle and by com- 

 pression of the tumour. Dubourg is said to 

 nave treated it with success by means of ex- 

 cision of the tumour and bringing together the 

 lips of the wound with needles, in the same man- 

 ner as in the operation for hare-lip. Beynard 

 tied a ligature round the sac. E. de Thine- 

 court compressed the tumour, after having 

 opened it, with two small rods, which he 

 connected and pulled together by means of 

 ribbons. The noxious effects of hydrorachis 

 after the child's birth make it necessary to 

 try an operation. Before birth this mal- 

 formation seems not to have the least in- 

 fluence upon the health of the child : it is 

 well nourished and duly constituted. After 

 birth the noxious effect is modified by the 

 different seat of the tumour. When seated 

 in the lumbar and sacral region, it is the 

 least dangerous. It is known that some indi- 

 viduals have lived with it twenty-eight years. 

 In most cases, however, paralysis of the in- 

 ferior part of the body is its consequence. 

 Hydrorachis in the cervical region is much 

 more dangerous. One case of this is men- 



tioned in my " Tabulae," in which death sud- 

 denly occurred on opening the tumour. 



Besides hydrorachis, some other malforma- 

 tions of the spinal medulla are observed some- 

 times to accompany fissure of the spinal column : 



1. Complete want of the spinal medulla, com- 

 monly connected with acrania ; 2. Its appear- 

 ance under a cylindrical form, with persistance 

 of the primitive medullary canal (Morgagni, 

 Santorini), which is sometimes double (Gall, 

 Von Ammon) ; 3. Fissure of the spinal me- 

 dulla into two juxtaposed cords; so that it 

 seems to be double, which is occasioned by 

 an arrest of developement at that period of 

 its evolution in which the two halves, of which 

 it is formed, are as yet separate ; 4. The pre- 

 sence of a simple nervous expansion instead 

 of spinal medulla; 5. The lamellar form of 

 the medulla ; 6. A too great length. 



By all this it is proved, that fissure of 

 the spinal column may be accompanied with 

 hydrorachis, and with an imperfect deve- 

 lopement of the medulla. They are totally 

 independent of each other, and each is pro- 

 duced by its own cause. It is, however, not 

 very improbable that a voluminous sac on 

 the medulla may prevent the union of the 

 points of ossification, by which the vertebral 

 arcs are to be formed ; but we are not, I think, 

 justified in concluding from this that hydro- 

 rachis is the cause of the fissure of the 

 vertebral column. For it may exist without 

 fissure of the spinal column, if it has not 

 acquired the form of a bag ; and the spinal 

 column may be cleft although the spinal me- 

 dulla is intact. This leads me to the con- 

 clusion, that malformation of the spinal me- 

 dulla, hydrorachis, and fissured spinal column, 

 do not essentially go together. 



IV. Hydrocephalus congenitus. 



Congenital dropsy of the brain. Under this 

 name we understand such a great volume of 

 the head in a full-grown foetus that it opposes 

 in general a mechanical impediment to partu- 

 rition, which can only be removed by an arti- 

 ficial diminution of the volume of the head. 

 Its forms are 1. Hydrocephalus internus ; 



2. Hydrocephalus eocternus. 



1. Hydrocephalus internus is said to exist 

 when the abnormal serous secretion occurs in 

 the ventricles of the brain, wherefore it has 

 also acquired the very rational name of 

 hydrops ventriculorum cerebri. It may be an 

 altogether primitive malformation, when the 

 brain is arrested at that period of its de- 

 velopement in which it has the form of a 

 very thin vesicle, filled with a serous fluid. 

 I have observed this condition principally 

 in Cyclopes, and give an example of it in 

 /#.614. 



In such case there is no indication of the 

 hemispheres, nor of the convolutions of the 

 brain, and, in general, no difference to be 

 seen between the white and the grey cerebral 

 substance. In small foetuses of two months, 

 in which the bones of the skull could not yet 

 be discerned, this form of hydrocephalus has 



