552 THE MEMBRANES
origin rather to the intestine than to the bladder itself. But in man and other animals furnished with incisors in both jaws, and in whom the allantois is wanting, the size of the urachus is so diminished, that although it rises from the fundus of the bladder as a single tube, it afterwards splits into innumerable fibres, which pass beyond the umbilicus together with the ves- sels, and carry the urine into the chorion, although the exact mode in which it does so cannot be demonstrated." On this ground he accuses Arantius of a double error first, his de- nial of the existence of the urachus in man; and, secondly, his assertion that the foetus passes its urine through the geni- tal organs.
For my own part, I must confess I am a willing party to the errors of Arantius, if errors they are to be called. For I am quite sure, if pressure be made on the bladder of a full- grown foetus, whether of man or of any other animal, that urine will flow by the genitals. But I have never seen an urachus, nor observed that the urine is propelled into the mem- branes by making pressure on the bladder. I have indeed seen in the sheep and deer what appeared to be a process of blad- der between the umbilical arteries, and which contained urine; but it in no way resembled the urachus as described by Fabricius. Not that I would obstinately deny the existence of an allantois; for the minor membranes are so delicate and transparent (those, for example, which we have described as existing between the two " \vhites" of the egg) that they may easily escape observation. Moreover, in the hen's egg a white excrementitious matter, and even faeces are found between the colliquament and albumen, i. e. between the amnion and chorion ; this I have mentioned before, and Coiterus has also observed it. Added to which, the membrane of the colli- quament itself, in which the foetus swims, although it is so exceedingly transparent and delicate that Fabricius himself allows nothing can be imagined more so, nevertheless (for accord- ing to him all membranes, however thin, are double) may nature sometimes find herself compelled to deposit urine or some other matter between its duplicatures. An allantois of this kind I am ready to allow Fabricius; but that other intestine-like body produced into either horn of the uterus, I do not discover among the membranes in cloven-footed animals, nor aught else, in
�� �
