DR. MINKS ON THE MICROGONIDIA OF LICHENS. 
35 
The presence of gonidia excludes the idea of lichens living as 
parasites on other plants or on bodies in a state of decomposition. 
They owe this to the chlorophyl they contain, which gives to the 
gonidia their colour. The granular contents of the gonidia consist 
principally of corpuscles which are the microgonidia and must be 
placed in a higher rank than the chlorophyl substance itself. 
These microgonidia are capable of arranging themselves in beauti- 
ful harmony contributing to the formation and increase of the 
gonidial cell without losing their independence, and playing a part 
which controls the whole development of the reproductive and 
vegetative life to the final end — the production of asci. The 
microgonidia maintained a globose form, slightly flattened, some- 
what like a convex lens, having in its centre a transparent and 
highly refractive nucleus, surrounded by a green zone, enveloped 
by a rather thin, white, protoplasmic layer, which is not always 
visible. In harmonious conformity to this structure all the ceils 
of the lichen body, even to the completion of its life — the asci — 
are more or less confined, maintaining this form even during all the 
phases of development and growth, during which the microgonidia 
enormously increase. There are two modes of increase — by 
division and by progemmation, the first altogether resembling cell- 
division. This proves that the microgonidia are protoplasmic 
bodies to which the existence of a membrane, at least in the most 
abstract condition, cannot at present be proved. The connection 
of the microgonidia with their cells is visible principally by the 
uniformity with which the simultaneous division of the cell itself 
and its microgonidia takes place. 
It is necessary to state that the intensity of the green of all the 
living gonidia certainly depends on the microgonidial cells alone, 
but essentially on the quantity and arrangement of these cor- 
puscles. It is possible that the microscopic image of the veritable 
gonidia presents itself as absolutely colourless, as do some “ metro- 
gonidia” (“ heterocyots ” “ Greuzzellen ”) of the Collemacece, be- 
cause the distance of the conglomerated microgonidia appears much 
more considerable all round the cell membrane owing to the re- 
fraction of the colourless parts predominating. For this reason 
also the microgonidia distributed in the hyphse have remained up to 
the present invisible, their cells always appearing destitute of green 
colour. But the impossibility of recognising this is accounted for 
by employing insufficient objectives to the microscope. The powers 
necessary to be used have already been named in the “ Revue.” 
Anyone having access to my work will, I am sure, by the aid of my 
figures find proof of the existence and activity of the microgonidia 
throughout all the process of vegetation and reproduction ; and 
he will readily perceive that these corpuscles are in fact the thread 
of Ariadne which ought to guide him through the labyrinth of the 
anatomy and morphology of lichens. 
The liomogeneousness of the hyphae of lichens and fungi has no 
