242 DR. KLEIN. 
rise to the formation of a system of intercommunicating 
sinuses, than it is seen that the whole of the deep layers 
of the rete Malpighii become inundated (so to speak) with 
migratory cells, which soon find their way towards the cavi- 
ties, and convert them into microscopical collections of pus- 
corpuscles, the formation of which is proved to be due to 
migration from the corium, not only by the actual observa- 
tion of numerous ameeboid ‘cells iz transitu, but by the fact 
that the corium itself, before so crowded with these bodies, 
becomes, as the pustulation advances, entirely free from 
them. 
Section [1V.— Anatomical Investigation of the General 
Eruption. 
The anatomical characters of the secondary pocks are 
substantially the same as those of the primary, the most 
prominent features being thickening of the rete Malpighii 
and oedema of the corium, combined with the presence of 
lymph-corpuscles around the blood-vessels, with similar cor- 
puscular infiltration of the lymphatic canalicular system in 
the neighbourhood. 
In general the stage of pustulation is reached more rapidly 
in the secondary pustules than in those which are the direct 
result of inoculation. Thus, in the eruption on the lips the 
contents of the vesicular cavities became purulent not later 
than the third or fourth day ; after the appearance of papules 
on the chest the development was more tardy. The infiltra- 
tion of the cutis and papillary tissue was greater towards the 
periphery than towards the centre, especially in those pus- 
tules that had lasted longest and exhibited most distinctly 
a central depression. ‘There were also considerable differ- 
ences as regards the changes which, in the primary pustule, 
result in the splitting of the rete Malpighii into two layers. 
The peculiar transformation which in the primary pustule 
goes on to such an extent as to result in the formation of a 
horny layer, which is of such thickness and so well marked 
that it can be distinguished in the section by the naked eye, 
is represented in the secondary pustules by a change of the 
same kind, which, however, is very partial in its extent and 
distribution, and affects only a few cells of the middle layer 
of the rete. Connected with this there is a considerable 
difference in the mode of the formation and the arrangement 
of the vesicular cavities. They appear in great number 
simultaneously in the middle layers of the rete Malpighii, 
and are generally found much nearer the corium than in the 
