This view of Leichtenstern, based upon the Old World hookworm (Ancylostoma duodenale), appears to be one that might in certain cases be of practical importance, and it seemed wise, therefore, to test it as applied to our American hookworm.

The opinion seems to prevail that in case of Ancylostoma duodenale the female worms are much more numerous than the males. Bearing on this point the following data are found in our notes (absence from library facilities at present prevents us from consulting some of the original articles):

Bilharz (1853, 55), Heller (1876b, 778), and R. Blanchard (1888a, 765) report 1 male to 3 females. White (1867, 427) states that the males are less numerous than the females. The following cases are reported with the number of males and females passed:

In the foregoing 11 cases it is clear that the females (78 per cent) are in excess of the males (21 per cent). In 7 cases from Schulthess the females and males were about 6 to 1.

Leichtenstern (1886, 216-217) quotes two series of cases from Schulthess, as follows:

In these two series also it is clear that the females (68 per cent) are in excess of the males (31 per cent). In the series of 26 cases the variation was between 10 males to 360 females and 10 males to 11 females.

Leichtenstern remarks that the males may roll themselves up in the feces and be overlooked. He also states that cases occur in

which only the females appear for two days after the anthelmintic; then the males appear.

From the foregoing statistics, based upon Ancylostoma duodenale, we were prepared to find similar conditions in the case of Necator americanus, especially since Lutz (who probably had Necator before him) is quoted as reporting for 3,000 worms a proportion of 3 females to 2 males.

In hospital work we usually have hookworm patients under observation only one day per week. It becomes necessary to inquire, therefore, into the number and proportion of worms passed in successive stools and on successive days in order to have an indication of the proportion of worms that escape collection on the day of

treatment.

Number of worms and proportion of sexes found in successive stools on day of thymol treatment. The stools may follow each other so slowly or so rapidly, namely, so ununiformly, that a tabulation by actual stools has been followed in only a very few instances.

Case No. 3 (age 21 years) of our 1911 series shows the following data on day of treatment; dose, 45 grains of thymol:

Although in the second stool the males and the females were not separated, it is clear that in the first stool the males were greatly in excess of the females, and therefore that they were not more difficult to expel.

Case No. 63 (age 16) of our 1911 series shows the following data on first treatment; dose, 10 grains of thymol. (The patient had received one treatment before he came to the marine hospital.)

In this treatment it is clear (a) that the female worms were i excess of the males for the total treatment (7 stools) and for stools Nos. 2, 3, and 5; (b) that the males and females were equal in stools Nos. 1 and 7; and (c) that the males were in excess in stools Nos. 4 and 6.

The two cases cited do not seem to give us any clue of practica. value in use of statistical data as to sexes in their order of expulsion in a given treatment.

In our notes we find two literature references for comparison. E. Parona, according to R. Blanchard (1888a, 765) reports a case as follows: First stool contained 8 males and 104 females, total 112 worms; second stool contained 16 males and 19 females, total 35 third stool contained 107 males and 66 females, total 173

worms.

Blanchard (1888a, 765) also reports a case from Leichtenstern as follows: First stool contained 10 males and 124 females, total 134 worms; second stool contained 28 males and 7 females, total 35

worms.

It is not clear to us whether Parona's case involved 3 courses of treatment or 3 stools after 1 course of treatment, but our notes give the following data for Leichtenstern's (1885, 101) case: First treatment, 15 extr. fil. mar.,' first 4 days; 10 males and 124 females, total 134 worms. Second treatment, 10 extr. fil. mar.,1 28 males and 7 females, total 35 worms. Total, 38 males and 131 females. Grand total, 169 worms.

Accordingly, positive data for comparison between Necator americanus and Ancylostoma duodenale, in respect to the point under discussion, are not available to us at present.

Duration of passage of worms after thymol.-In hospital work the average hookworm patient is, as stated above, usually under observation for only about 18 to 24 hours at a time. He is admitted to the wards late in the afternoon or early in the evening. He takes his thymol the next morning. By 1 to 4 o'clock in the afternoon he is over the effects of the salts and thymol to such an extent that he either desires to go home or from a financial (administrative) point of view there is little or no justification in retaining him longer. Accordingly, under ordinary circumstances, opportunity is presented to collect the worms passed only up to 3 or 5 p. m. of the day of treatment. While this permits, doubtless, the collection of most of the worms, a number escape the observer, for they continue to pass for three or four days or more, as the following cases show.

1 German equivalent for Oleoresina aspidii of the United States pharmacopoeia.

From the foregoing cases it is clear that all worms expelled by a given course of treatment need not necessarily be passed on the day of treatment, but while about 75 to 95 per cent of the specimens expelled may be passed within 12 hours after the drug is administered, worms may continue to pass for 5 or 6 days.

It further seems evident from the foregoing records that the males and females do not follow any regular order in passing which can be used as a practical indication as to the completeness or incompleteness of the cure.

Two practical conclusions are to be drawn from the foregoing data. (1) Since 75 to 95 per cent of the worms pass during the first 12 hours after administration, all hospital records that give the number of worms collected during this period are subject to a theoretical error of about 5 to 33 per cent; that is to say, the actual number of worms passed may be from one-twentieth up to one-third larger than actually reported. This point should be borne in mind when comparing statistics derived from treatment with statistics derived from autopsy not preceded by treatment.

(2) It occasionally occurs that on the day of treatment not a single worm is collected, but later microscopic examination is negative. Probably the correct conclusion is that the worms have been passed after the patient has been discharged.

Proportion of male and female hookworms passed after thymol treatment. In nearly all of the following cases the worms were collected