188 
AN ACCOUNT OF SOME HELMINTHES COLLECTED IN THE SUDAN 
Action of 
alcohol 
Rapid method 
of examination 
Trematodii 
tissues. The preservative reagent, i^ar excellence, for the Nematodes is alcohol, but its use 
must be governed by certain rules, otherwise the inevitable contraction and shrinkage will 
occur. 
Looss has found, by e.xperiment, that if living Nematodes be dropped into boiling 70 per 
cent, alcohol they will die extended and without local distortions, and that such specimens may 
thereafter he slowly infiltrated and rendered transparent hy glycerin. For field work in the 
Tropics, and to olitain most satisfactory results, it is only necessary to he provided with a supply 
of spirit, a large test-tube, a brass spirit lamp, and a small enamel pan 3 in. by 3 in. The pan 
should be of just such a size as will contain the lamp within it and thus reduce the space to a 
minimum. The pure spirit suffices for the lamp, and when diluted to the strength of 70 per 
cent, alcohol it serves as reagent. The specimens when collected are shaken up vigorously in 
half a test-tube of 1 per cent, saline solution, in order properly to cleanse the mouth parts and 
genital papill® of foreign matter, and then poured out into a fiat vessel—petrie dish or an 
ordinary plate. A quantity of the 70 per cent alcohol solution is then poured into the enamel 
pan, filling it to the depth of about half-an-inch. It is then heated over the spirit fiame until it 
just commences to boil. Thereon the pan is (piickly raised from the fiame, and the specimens 
are rapidly transferred one by one from the saline solution. They should immediately straighten 
themselves out and die in an extended condition. When all the specimens have been killed 
in this way they should then he transferred to small tubes of cold 70 per cent, alcohol, in 
which they w’ill remain without shrinking or becoming brittle for a long time. 
For examination the specimens must be further treated in order to render them trans¬ 
parent. If small, or if external anatomy only is required in larger w'orms, they should be 
cleared in glycerin. The worms are taken from the 70 per cent, storage alcohol into a 
solution of 70 per cent, alcohol to which has been added 5 per cent, of pure glycerin. The 
whole is then allowed to evaporate slowly, say in a temperature of al)out 60° C. The alcohol 
is gradually driven off, leaving the glycerin to become more and more concentrated ; the 
process not being completed until there remains only a small quantity of very viscid glycerin 
containing the w'orms. The specimens then may be examined immediately, stored in pure 
glycerin, or mounted in glycerin-jelly as permanent preparations. Should a more rapid 
examination he necessary than is allowed by the above method, the specimens, after fixation in 
boiling 70 per cent, alcohol, may be transferred for thirty minutes to 96 per cent, or absolute 
alcohol, and then cleared in “white” creosote. This renders the specimens exceedingly 
transparent, so that even the histological details of the different internal organs may all be 
observed by various focussing. It is well suited for the study of the relationships of the 
internal structures of the larger and more opaque forms, and has an additional merit—that 
in the course of tw*enty-four hours the creosote will, by slow endosmosis, restore to normal 
contour any irregularities that may have been caused by the spirit. The cleared specimens 
should be examined in creosote and then returned for storage to 70 per cent, alcohol, as 
they do not mount satisfactorily in Canada balsam, and become deeply stained if they are left 
for any length of time in creosote, though in other respects they are uninjured and still retain 
their natural softness and contour. The 70 per cent, alcohol is much the best stock solution 
for museum purposes, for the specimens are then available at any time for investigation or 
reference by either of the above processes, and they are not rendered brittle, as by spirit, 
in course of time. 
Trematoda.- The only apparatus required for the Trematoda is a supply of test-tubes and 
collecting bottles, and the following reagents : 1 per cent, saline solution, saturated corrosive 
sublimate, 10 per cent, formalin, 70 per cent, alcohol. The saline solution is used as a cleansing 
reagent; the specimens are shaken up vigorously in it and the debris decanted off. For fixing, 
the following methods are best: The cleansed worms are transferred to a clean test-tube 
