Seventh in which some cranial bones are found. — This has been observed by Herholdt, in a monster, born twin with a Well-formed child, of a mo ther who had five other children. There was an amorphous head, with an indication of eyes and nose, but without ears and mouth : the rest of the body was much de formed. Of the cranial bones, the condyloid and vertical portions of the occipital only could be distinguished. There was no trace of facial bones. Analogous observations have been made by Curtius and Otto.
Eighth Type. — Body and extremities per fectly well developed, and having a neck, which is wanting in the other types. The neck is sur mounted and terminated by the ears. — This is the form to which Gurlt gives the name of perocephalus aprosopus. I have met with it in the lower animals only. The body and the limbs are perfectly well developed; on the perfect neck are placed two coalesced ears, behind which there is an imperfect cranium, composed principally of the cranial, minus the facial, hones. In all this the deformity makes a transition towards an imperfect formation of the face. (Figs. 620, 621.) Ninth Type. — Acephali which are composed of the trunk only, without the least indication of superior or inferior limbs. — Only one case of this monstrosity is known, observed by Vallis neri. In a foetus of a very mature period of evolution, the head, the superior and the infe rior limbs, were wanting. There existed only a trunk, which contained a tolerably large heart, imperfect lungs, a ma'formed liver, a stomach, and an intestinal canal.
From this survey of the characteristics which distinguish the acephali, we learn that they are born with two, three, or four other foe tuses at one birth. Can this quantitative multiplication of the children be the cause of the qualitative malformation of one of them ? This is probable by the great fertility of the mothers of acephali, which also indicates that these monsters are produced by an arrest of development. It is very easy to reduce their external appearance to the early periods of developement, in which the head is not yet distinct from the trunk, and in which the limbs are not yet protruded. It is worth mentioning that the abdominal cavity, with the kidneys and a part of the intestinal canal, are the most constant organs, which is very interesting with reference to the genesis of the intestinal tract. In the monstrous births of the second, third, and fourth type, there is only a colon, while in those in which a tho rax is superadded (as in the fifth and sixth types), there is also an intestinum tenue with the cxcum. I regard this as a confirmation
of the statement, that the formation of the intestinal canal commences at the two ex tremes, and proceeds from these to the mid dle part.
In the same manner the uniformity of cir cumference of the whole intestinal tube is an arrest of developement at an early period of embryogenesis, to which may also be referred the meal beginning, and in many cases even the ca.cal termination of the intestine. The fre quent deficiency of the liver is the consequence of the absence of the stomach and duode num, and therefore a sign that the liver is a protrusion of the mucous membrane of the in testinal tube. The connexion between the con taining and the contained parts is also very dis tinctly proved by the acephali. The very gene ral presence of the lumbar part of the spine determines the existence of kidneys ; that of the pelvis, the existence of the urinary-bladder and of the genital organs. The very imper fect condition of the thorax is in relation with the absence of the heart. The pre sence of vessels without a heart demonstrates that the circulation of the blood can be car ried on by these alone, and that the forma tion of vessels is quite independent of that of the heart. The profusion of cellular tissue, by which the swollen appearance of the acephali is produced, may be formative sub stance, which has not been employed in the production of the other parts of the body, and which has therefore grown rather abundant. In this manner many of the peculiarities of the acephali can be reduced to fixed principles.
VI. Want and defective Formation of the Trunk* (Acorn:jut).
The highest degree of this kind of mon strosity is where neither trunk nor limbs are formed. Lycosthenes, Rudolphi, and Nichol son describe monstrous births, in which the head is the only part formed.
a. Sometimes only a part of the head is ormed, of which I saw an example in a mon strous fcetus born with a well-formed calf. The tongue was the only well-developed part in it. This shows that in the absence of all the central organs, heart, lungs, skeleton, and brain, there may be a well-constituted skin surrounding an amorphous mass of cellular tissue, and only a single well-formed organ. I have given a fuller account of this case in my Tab. lxii. figs. 4, 5, 6. Therefore we may conclude that each part is formed speak suit', and that it is in its evolution quite indepen dent of the rest of the body.