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distance from the site of insulation increased. The resistance offered to the in-
vading organim,being insufficient to destroy it, trained it,as it ware, to develop
sere inimical powers of attack, so that the basilli everemo susssssively the bar-
riers placed in their path, they increased not only in virulence but in number alse,
just as the Virus fixe of rabies was obtained by Pasteur by means of passage of the street virus through a series of animals. This precess has been designated a "rein-
forement by relays," The evorsoning of this resistense by an organim of feeble
aggressive peware of course takes time, whether the delay is caused by the mall am-
ber of organima,er by their being of rodused virulmos,er by the greater degree of resistance set up leading to a "rolatively redused virulence," One or other of thesO
noting singly or in sembination may be addused te kosomit for latenay,
There cases are met with in which death saœurs at such a tender age as 22 days
214 (No 128), 24 days (No Skk), 29 days (No 180),and 7 wenke (Nos 63 and 114), one is naturally led to enquire inte the question of sengenital and hereditary tuberculosis,
The possible modes of congenital infestion are,of course, either by the svim or spermateseen, or viâ the plasenta from a tuberculous mother. As regards the first of these, as Adami states, "the misrobe of an infectious disease cannot be a sen- stituent of the biophere. At most it can be an aesidental inclusion in the sur- rounding won-heritable matter of the sell." The humanı evim,being prastically free from yelk and not being phagocytis, cannot take up the basilli, while it is still sera improbable that the minute spermatozoon could carry them. Rozoatod observationi go to show that the semen of a phthisisal patient (Rohlff,Osertaer) does not sentals ka many af ten basilli,and as the average human seminal ojasulation is said to contain over 200 million spermatesen, the shanses that a single spermatozoon which fertilises the ovim should sarry a basillus are about one to 20 million. For pract ical purpesos this mode of infection may be regarded as impossible. The second nethed, viêl the plasmta of a tuberculous mother (or perhaps through the walls of the foetal sas,er passing to the foetus before the one forma) has been shown to be possible; in fast,intra-uterine asquirement of disouso na distinst from inherited disease is proved. Such transmission of the tuberele bacillus from parent to shild in utere is,however, undoubtedly very rare, Thus Schluster, she examined into the records of the reported enves,as mentioned by Lathan, was able to sellest only twelve showing elinical evidence of tuberculosis at birth, Furthermore,in the
bein
majority of instances, the organs of factuses hase of tuberculeus mothers yield
enly negative results when inseulated inte guinea-pigs,