Researches into the structure and development of a newly discovered parasitic animalcule of the human skin, the entozoon folliculorum / by Erasmus Wilson.

  • Wilson, Erasmus, Sir, 1809-1884.
Date:
1844
Catalogue details

Licence: Public Domain Mark

Credit: Researches into the structure and development of a newly discovered parasitic animalcule of the human skin, the entozoon folliculorum / by Erasmus Wilson. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    the abdomen is long, it is frequently seen to present a succession of curves and to assume an undulated position. Besides flexion, the abdomen is capable of contraction both in the longitudinal and horizontal direction. I have sometimes seen one or two horizontal contractions which have straitened the diameter of the cylinder very con- siderably, and have given it the appearance of being tightly constricted by a string. The structure of the interior of the abdomen, like that of the thorax, is difficult to determine, on account of the extreme transparency of the animal and great number of adipose vesicles which, in clusters of various sizes, form the subcutaneous stratum. Externally to this stratum is a thin membrane which lines the epidermic case, and which, under compression, I have sometimes seen separated to a greater or less extent from the latter. The more general appearances of the abdominal contents are,^—a large, rounded or oblong mass of a light brown colour, situated close to the thoracic extremity; another light brown mass at about one third from the extremity of the tail; an irregular cellular mass between the two former, and a transparent portion at the caudal end. The most anterior of these masses is composed of nucleated gra^ miles ; in one instance it presented a distinct pouch-like figure with well-defined boundaries, but more usually it is irregular in form, sometimes extending for a short distance into the thorax, and at other times being prolonged by a pointed process backwards. Whatever its form, it is traversed through the middle by a curved, cylin- drical canal, which appears to represent the stomach, the dark granules being very probably hepatic corpuscles. The cellular mass which succeeds the gastric organ consists of an assemblage of transparent vesicles of various magnitude, some large and some small. In the midst of these the alimentary canal may generally be traced as a slightly shaded band, somewhat curved in its course. The third mass, namely, that which occupies the commencement of the posterior third of the abdomen, is composed, like the first, of nucleated granules or cells: this mass is smaller than the first; I have been unable to trace the alimentary canal through it, and I am inclined to regard the granules as constituting the ovarium. The remaining part of the abdo- men I have described as being transparent and empty of granules; this, however, is not constantly the case, for the granules sometimes extend to the very extremity of the abdomen. In a few instances I thought that I could perceive the latter part of the alimentary canal passing through this part of the animal and terminating by a dilated cloaca at the anal aperture. In the course of my observations on the Entozoon folliculorum, I have distinguished two principal varieties of the adult animal which are marked by strongly character- istic, if not by specific features. The first of these is of large size, fine proportions, and is remarkable for the great length of its abdomen and the roundness of its caudal extremity. The second is characterized by a certain degree of clumsiness of form, shortness of abdomen, and pointedness of the caudal extremity. The long form varies in size from the to the ^ of an inch in length ; the latter measurement, that is, somewhat more than a quarter of a line, being that of the