744 



SOLIPEDA. 



composing it as they recede from the umbi- 

 licus. 



The allantoid in the mare does not form a 

 closed bag, as it does in the ruminants, but 

 lines about half of the interior of the cavity 

 that exists between the amnion and the cho- 

 rion. To form an idea of this cavity and of 

 the space occupied by the allantoid, it will be 

 necessary first of all to consider the amnion 

 as a sac, in which the foetus is enclosed, and 

 the allantoid and the chorion as forming an- 

 other sac of larger size, by which the former 

 is enveloped in such a manner, that an inter- 

 space is left between the two : this interspace 

 is traversed by the second portion of the 

 umbilical cord as it passes from the former 

 sac towards the latter, and in this course, the 

 cord is enveloped by the allantoid membrane, 

 which subsequently invests all the interior 

 of the second sac formed externally by the 

 chorion. 



The aperture of the urachus pours forth 

 a glairy fluid of a reddish colour, which is re- 

 ceived into the cavity, the boundaries of which 

 are described above : this fluid has a urinous 

 smell, especially when heated, and moreover 

 contains certain solid bodies, which have been 

 from time immemorial dignified with the name 

 of hippomanes, and were by the ancients sup- 

 posed to be possessed of various mysterious 

 qualities, and magical influences. 



The Hippomanes was considered, until a 

 very recent period, to be a piece of flesh 

 growing upon the forehead of the nascent foal ; 

 and it was not until Daubenton presented a 

 memoir upon this subject to the Royal 

 Academy of Sciences in Paris *, that its real 

 nature was understood. The hippomanes 

 were then found to be merely masses, of a 

 thick substance, of variable dimensions, con- 

 tained in the allantoid cavity, which, although 

 they might occasionally during parturition 

 after the laceration of the membranes, become 

 adherent to the head of the foetus, are, in 

 reality, produced between the 

 amnion and the allantoid mem- 

 branes. 



These bodies are very variable 

 in their size, and frequently several 

 are met with, the dimensions of 

 which vary from the size of a pea 

 to that of a large pear, some of the 

 latter weighing as much as five or 

 six ounces. They are composed of 

 a viscid substance of an olive brown 

 colour, and frequently have irregu- 

 larly shaped cavities in their inte- 

 rior ; but they present no traces of 

 organization. When cut into they 

 seem to be made up of numerous 

 superposed layers, and externally 

 their surface is covered with float- 

 ing filaments : sometimes they are 

 found to be attached by long pe- 

 dicles to the walls of the allantoic 

 cavity ; but, whatever their shape, 

 they are evidently merely sedi- 

 mentary deposits from the fluid in 

 which they are immersed, and in- 

 deed may be formed at pleasure 

 by slowly evaporating the contents 

 of the allantoic sac. These struc- 

 tures are indeed by no means pe- 

 culiar to the horse, but are fre- 

 quently met with in other animals. 

 The exterior of the chorion is 



A everywhere in contact with the 



Anatomy of the grand utens of the mare. (After Daubenton.} ^^ wallgj and in ghape ^^ 



a, the urachus emerging from the umbilical opening of the foetus, sents exactly the interior of the 

 accompanied by the umbilical vein ; b, and by two umbilical arte- cornua uteri, upon which it is 

 ries; c, continuation of the umbilical cord as far as the expansion moulded the placenta occupying 

 of the amnion; d, d, e, termination of the urachus; /, continuation ., ffrpat ' nor Hon of its extent 

 of the umbilical cord; g, g, allantois ; h, the chorion; i, an hip- tne g reater portion ot its extent. 

 pomanes adherent to the allantoid by its pedicle ; k, I, m, two other Mammary Glands. It was ge- 

 hippomanes of smaller size. The other letters refer to the genera- nerally believed from the time of 

 tive organs of the foetus (a female) shown in connection with the Aristotle until a very recent period, 

 above parts ; o, the rectum ; P , the anus ; q, the bladder of urine tnat j n the male horse there were no 

 communicating with the urachus; r, r, the ureters; s, canal of the 

 vagina; *, orifice of the urethra ;%,, first appearance of the mem- 

 brane, which subsequently spreads over the urethral orifice ; x, x, 

 the cornua uteri ; y, separation between their internal cavities ; z, 

 2, the ovaria. 



rf 

 ot 



* Me'moires de PAcade'mie Royale 

 des Sciences, annees 1751 and 1752. 



