68 OBSTETRICAL PHYSIOLOGY. 



drawn. The Stallion is then allowed access to the Mare, and within 

 five minutes after copulation the tube is extracted by means of a tape 

 attached to it, the end of which has a ring, and hangs outside the 

 vulva. 



Moderate rigidity of the cervix, which cannot be overcome by prompt 

 manipulation, may be combated by means of sponge tents introduced 

 into the os. These are made by soaking a sponge of the necessary size, 

 and to which a long string is securely tied, in a strong solution of gum 

 arable ; it is then closely wound round with a thread, so as to form an 

 elongated, pointed mass four or five inches long. When dry the thread 

 is removed, and the sponge, being slightly smeared with grease or 

 glycerine, is passed into the os, where it is left to soften and expand, in 

 doing which it widens the canal. In some instances it may be neces- 

 sary to assist the dilatation by making some slight incisions through 

 the cervix. 



In rare instances complete dilatation may require to be effected by 

 a cutting instrument, but this should never be resorted to until the 

 simpler and safer means have failed. 



Disease of the mucous membranes, with altered secretions, must be 

 treated according to the indications. 



CHAPTEK IV. 

 Changes in the Ovum. 



During the progress of the ovum towards the uterus, and soon after its 

 reception into that cavity, some remarkable alterations occur. The 

 ovum has encountered the fructifying element of the male semen — the 

 spermatozoa ; at least, this has been established in the Rabbit, in whose 

 oviducal ovum they were found to have passed through the zona pelliicida, 

 though no opening has yet been discovered in that extremely fine 

 evanescent film. The germinal vesicle disappears, or has changed its 

 character, and a somewhat more opaque cmhrijonal cell succeeds, which 

 may be, or includes, a combination of the nuclear matter of the sperm- 

 cell with that of the germ-cell. Then the vitellus, escaped from its 

 enveloping membrane, becomes depressed in a circular manner, and 

 breaks up into independent masses. 



This change, and others to be described, takes place during the course 

 of the impregnated ovum through the Fallopian tube. It may chance, 

 however, that impregnation takes place in the uterus ; for it is probable 

 that the ovum may be retained there for a certain time previous to 

 perishing or being ejected, and that, should it meet the spermatic fluid, 

 impregnation will ensue and the usual results follow.^ But it is more 



^ It may be remarked that, with multiparous animals, the number of young in the 

 cornua are not in proportion to the corpora lutea of the same period. Franck mentions 

 an instance in which there were eleven corpora lutea and only five foetuses ; from which 

 it might be inferred that six ova had perished, or, if they had been impregnated, that 

 the fcBtuses must have died at a very early period, and been absorbed. It has also been 

 stated that an ovum from the right ovary (which bore recent traces of the rupture of a 

 Graafian vesicle), has been found in the left cornu, whither it must have wandered. 

 This has been observed in woman, in the Bitch, the Guinea-pig, and also in the Sheep. 

 Kehrer, in the MonaUachrift filr iJeburtshnnde (vol. xxii., p. 225), mentions finding a 

 fcetus in each horn of the uterus, and in the right ovary two true corpora lutea. One 

 ovum had migrated to the left cornu by means, probably, of the uterine contractions. 



