Dissertations by eminent members of the Royal Medical Society.

  • Royal Medical Society of Edinburgh
Date:
1892
Catalogue details

Licence: Public Domain Mark

Credit: Dissertations by eminent members of the Royal Medical Society. Source: Wellcome Collection.

    318/336 (page 302)
    ception, during which a woman is not pregnant. By this interval, then, all such cases must be curtailed. Very little has as yet been ascertained as to the possible length of this interval. It was my inten- tion to have attempted to make it out in regard to some of the lower animals ; but my inexperience in such investigations, and the pressure of other avoca- tions, have hitherto deterred me from the pursuit of this subject. There is then at present no resource in this question but to facts already known. Now it has been ascertained by physiologists that semen newly expelled by the male is not essential to im- pregnation. Animals have been frequently impreg- nated by Spallanzani and others with semen which has not only been kept for some time, but has even been variously altered, in mechanical properties at least, in experiments. And there seems to be no limit to the time during which the semen may be kept without losing its virtues, except the term of the hfe of the spermatozoa. That this period is not insignificant, and cannot be passed over without risk of important error—in fact, that it may extend to many days or weeks,— will appear from the following observations. We omit the facts in regard to animals so low in the scale as insects, in the females of which the semen is laid up in cavities where it retains its power for months. In regard to the dog, Leeuwenhoeck pointed out that these animalcules might live for more than seven days preserved in a glass tube, and if such be the case in a rude experiment, it may be expected that they should retain vitality consider- ably longer in the passages of the bitch, where they have heat and moisture supphed under pecuhar