206 CORRESPONDENCE. 
considers that wliat Nowakowsky takes for conjugation is a simple 
fusion of kypka-tlireads, and has nothing to do with formation of 
resting spores. Assuming, therefore, that all Basidiomycetes (in the 
Brefeldian sense) are reproduced asexually, we see starting from 
Entomophtliorece gradual elimination of the resting-spore element 
accompanied by complication of the ordinary fruit. The Ustilaginece 
also come into the series, only here instead of the resting spores being 
merely one form of reproductive organ, they are the main form, since 
reproduction by gonidia and by ordinary spores occurs only on 
germination of the resting spores. With regard to the Uredinece, the 
JEcidium fruit is held to be the analogue of the resting spores of 
Entomophthorece and Ustilaginece , the spermogonia corresponding to 
the gonidia of the former, and to the club-shaped sexual cells of 
Tremellinece, while the teleutospore fruit is a true basidiomycetous 
fruit, the teleutospore being merely the expression of adaptation to 
external conditions and producing true basidiospores as the result of 
its germination. Dr. Brefeld agrees with Sachs in considering that the 
Zygomycetes and Oosporece have been derived from Algte. For them 
he adopts the old word Phycomycetes. The rest of the Fungi are 
divided into two groups, Myxomycetes and My corny cetes, the latter con- 
taining Basidiomycetes, Ustilaginece, ZEcidiomy cetes, and Ascomycetes. 
. 
CORRESPONDENCE. 
Dr. Edmunds’ Paper on a Paraboloid Illuminator. 
To the Editor of the ‘ Monthly Microscopical Journal.' 1 
Sir, — I fully endorse the remarks of Dr. Edmunds, in favour of 
the effects of the above illuminator. The idea is, however, by no 
means a “ new ” one, and has long been published and figured in the 
Transactions of the Microscopical Society. At the meeting on 
March 20, 1856, I read a paper on illumination, and described a 
small truncated parabola of crown glass used beneath the stage, on the 
flat top of which slides were to be laid with an intermedium of high 
refractive power. Animalcules, or objects in water, or other fluid 
were placed directly on the flat top, and covered with thin glass. 
Beyond making two of different sizes for my own use, and exhibiting 
the effects on that occasion, I made no further stir in the matter, and 
it has since been twice reinvented. My reason for devising this was 
on account of a difficulty in obtaining a perfectly black field under 
large angles of aperture by means of the ordinary paraboloid. In 
this I was then successful. I remarked in my paper of the truncated 
or “ immersion ” paraboloid that “ the light may be obtained of any 
required degree of intensity and the field perfectly black with 
objectives of the most extreme aperture.” 
Dr. Edmunds remarks in his paper (page 84) that from “ a 
paraboloid the illumination of an object may be made to reach the 
point where it could be taken up from above the stage by a fine 
parabolic Leiberkuhn, or other reflecting appendage to the objective.” 
This idea I also carried out many years ago : it is figured and 
