2 
Parasites are not at all easy to deal with; when taken out, everything — except 
perhaps tolerably large females and ovisacs — must be kept in glycerine on an object- 
glass, for if males, pup, etc. are put in spirit, they are generally difficult to find and to 
get out of the tubes. For this use the glycerine must always be strongly diluted with water, 
otherwise the animals shrink very much, and the females especially are very apt to lose 
their shape. The water is made to evaporate by standing exposed to the air. Neither the 
females nor the males nor the animals in any stage of development, can bear the pressure 
of a glass-cover, or of part of it, without losing their natural shape. In order to make 
drawings of the entire animals or of parts of the females, the following method was employed: 
I took very small covers (frequently a middle-sized cover was cut into four parts), and 
placed a very thin wooden wedge under the middle of the back edge of the cover, so that 
by very carefully pulling the wedge a little, I made the glass touch the animal, or part of 
it, just sufficiently to keep it in a certain position; by means of a hair, which was introduced 
through the opening, its attitude could easily be changed. In this way I was able after 
some practice to manipulate a male of the length of '/smm., so that I could make accurate 
illustrations of one specimen seen from below and sideways without damaging it at all. 
After use the animal and all the parts that had been examined were placed under a large 
elass-cover in the way described above, and the opening was closed with varnish. The 
female was always dissected, in order to submit the head and the genital area to a careful 
examination. The latter part was treated in the following way: with a sharp and very 
small knife I cut through the animal a little above the genital region, after which this part 
was placed under a simple microscope which magnified it a hundredfold; the inside of it 
was cleaned with a knife, so as to leave only the muscles of the genital apertures and one 
or both of the receptacula seminis. I specify this proceeding, which I learned by degrees 
through rather troublesome experiences, partly that the reader may judge of the accuracy 
of my illustrations, partly to enable future students, who may not possess such ample material, 
to conquer the difficulties with comparative ease. 
As far as possible, I have everywhere given figures of an adult female, a male and 
an oyisac (Sometimes adding one or two pupz) magnified to the same scale, in order to show 
the relative size of the two sexes, the ovisacs and eggs. The size of the male compared. 
with the female and the ova varies very much in the different species. For the convenience 
of the student, and in accordance with earlier statements (1890), I have always figured the 
males vertically from the ventral side and laterally from the left-hand side. While in 
symmetrically shaped Arthropoda, in dorsal or ventral view, I generally arrange the position 
of the legs and figure those on one side to correspond with those on the other, with the 
parasites described in the present work I have not ventured to do this. The animals were 
often a little crooked on account of a slight pressure, to which they had been exposed in 
the marsupium; maxillipeds and legs were found straddling in different directions, and as a | 
rule were too small to allow of much alteration in their attitude, without great risk of 
