84 THE NORTHERN MICROSCOPIST. 
they have just left the body of the parent they are extremely small, 
measuring only about ggooth of an inch in length. The parasite is 
cylindrical and narrowed towards the anterior end, the posterior 
end being obtuse and rounded. Fig g is an illustration of a 
muscular bundle infested with trichinze, which are shown of their 
natural size as small white spots, while a section of the same 
magnified 30 diameters is shown in Fig. to. 
In the agamous state the worm is coiled upon itself in its cyst, 
over which there has been some amount of discussion. This cyst, 
or larval chamber, grits under the section knife, and dissolves in 
hydrochloric acid without effervescence, and therefore, according to 
Bristowe and Rainey, consist of phosphate of lime; Kiichenmeister, 
on the other hand, holds that they are formed of carbonate of lime; 
while Davaine bringing his experience to bear upon the matter, 
though stating that the absence of effervescence is no proof of the 
absence of carbonic acid, since the small quantity which is evolved 
might remain dissolved in the surrounding liquid, hints that 
carbonate of lime might be a normal constituent of the cavity of 
the cyst. 
When the agamous state present in the muscle of a pig is 
introduced into the alimentary canal of the human economy, the 
immature worms escape from their cysts, develop their sexual 
organs, and produce young at avery rapid rate; the new generation 
piercing the walls of the digestive system, enter the muscles where 
they become encysted. 
The vital resistance of Zrichina spiralis is very considerable. 
It will live in cancerous tissue, and when plunged into a freezing 
mixture maintained at —20° C (—4° F.) they have been found 
alive after 72 hours. Protected by their cyst they require a 
temperature of 70°—75° C (158—167° F) to kill them ; while when 
heated to 60° C (140° F) in the muscular fibre they become very 
lively. Deprived of their protecting cyst and submitted to a tem- 
perature of 67° C (153° F) they still move, and when meat infected 
with trichinz has been buried and in putrefaction for over five days, 
they have still been found living. 
In Germany, microscopes are made specially for Trichinal obser- 
vations; several were described in the August number of the Journal 
of the R.M.S. ; but any good firm microscope stand with a mechanical 
stage, so that it may be used in such wise as not to miss any part of 
the object during the search, is sufficient for the purpose. Armed 
with a double nose piece, and good objectives of 1" and 4%" power, 
together with an extra large and strong compressorium, the observer 
should be able to detect trichinz without mistake. 
It is necessary to examine fragments and sections of those 
muscles which are most frequently attacked, the latter can be cut 
with a Valentin’s knife when the substance is not too hard and dry. 
