Laboulbenia chaetophora and L. Gyrinidaru m . 32 7 
The most serious difficulties in the way of technique, apart from those 
of obtaining suitable and adequate material, have been the securing of 
proper infiltration of the reagents used, and the sectioning of the embedded 
portions of the host. The chitinous external wall of the fungus impedes 
the ingress of fixatives and often prevents it. Hot fixatives were sometimes 
employed, and in some instances gave excellent results, but by far the best 
were obtained by making an incision in each plant in the manner to be 
next described. 
Preparatory to fixing, portions of the insect bearing the fungus were 
dissected off with scalpel or scissors, as little as possible of the integument 
of the insect being taken. Immediately after detaching such a piece, it 
was laid in a drop of the fixing fluid on a slide, and with the aid of a dis- 
secting microscope and a pair of chisel-pointed needles the ends of the peri- 
thecia were snipped off. For this purpose needles with the finest points 
obtainable were mounted in match-stick handles and the points ground down 
to a sloping chisel edge. The material was then at once transferred to 
a phial filled with the fixing reagent. In the case of young plants the 
application of such technique was impracticable, and they were fixed without 
snipping, with the result that not infrequently fixation was not good. 
Snipped and unsnipped mature perithecia were sectioned by way of com- 
parison. The former were invariably better preserved, the latter usually 
so badly as to be unusable. Several reagents were employed, but Flemming’s 
weaker solution proved to be most satisfactory and was finally exclusively 
employed. As for stains, there is little to choose between Flemming’s 
triple and Haidenhain’s iron haematoxylin, the choice possibly resting with 
the former. 
In order to overcome the obstacles offered in sectioning the host, some 
attempts were made at detaching the plants, usually during the embedding 
process, and handling them individually. With the larger subjects this can 
be done successfully, and by improving the methods possibly with all. But 
on account of their minuteness there is bound to be more or less loss in 
such a procedure, and as this is a serious consideration where material is 
none too abundant to begin with, this method was not very extensively 
employed. 
By embedding in paraffin with a melting point of from 57 0 to 6o°C., 
and cutting with a hard knife, sections from 3 to 5 microns can be obtained, 
though the chitin of the host almost invariably fractures before the knife. 
In order to soften this chitin, experiments were made by immersing the 
material in a solution of eau de Javelle after it had been hardened. This 
method was useless, however, because, while it dissolved the chitin, it also 
rendered the plants quite colourless and caused them to loosen from their 
points of attachment. 
