FRUCTIFICATION OF CHOANEPHORA. 419 
allied to one another than to the conidia. They are new and independent cells formed 
within the tubular system of the parent plant; but the conidia are merely isolated 
portions of that system, being, in fact, merely the tips of the terminal filaments of the 
aerial portion of the plant. The distinction, moreover, is not merely an anatomical one; 
the difference in the nature of the conditions favouring the development of the various 
forms of fructification indicates a physiological distinction also, The conidial fructifica- 
tion is the form characteristic of active nutrition and vegetative growth. Given a very 
rich nutritive medium and fully developed normal conidia, a luxuriant development 
of mycelium occurs, followed, sooner or later, by an abundance of conidial fructification. 
With diminishing nutrition there is progressively poorer mycelial development and less- 
developed conidial fructification. When this degeneration has reached its utmost limit, 
when the conidial fructification is reduced to its poorest and simplest type, the sporangia 
begin to make their appearance; and when conditions of nutrition are too greatly 
lowered even to allow of this, we find the chlamydosporic fructification providing for the 
preservation and diffusion of the plant. 
The fact that the occurrence of various forms of fructification may be determined by 
conditions of nutrition should be constantly borne in mind in the study of organisms 
with polymorphic reproductive apparatus. The observation of the fact isnot a new one; 
but the present instance appears to be one of the clearest demonstrations of it which has 
yet been afforded. It is not, however, merely in respect of this, although no doubt 
closely associated with it, that the phenomena exhibited by Choanephora deserve atten- 
tion. They appear, in addition, to be capable of affording a possible explanation of 
certain conflicting conclusions which have been arrived at as the result of recent 
observations on the Mucorini conducted by highly competent authorities. I allude 
especially to those of MM. Brefeld, Van Tieghem, and Le Monnier. The former author 
has been led by the result of his observations to divide the Mucorini, or Zygomycetes 
as he prefers to style them, into two subfamilies, one of which he distinguishes as 
characterized by sporangial, the other by conidial asexual fructification. MM. Van 
Tieghem and Le Monnier, on the other hand, deny that true conidial fructification 
ever occurs in the Mucorini, and affirm that in those cases where it has been stated to 
occur, the supposed conidia were either monosporous sporangia or aerial chlamydospores. 
The phenomena presented by Choanephora show both these conclusions to be incor- 
rect; for, on the one hand, they demonstrate that true conidia really do occur in the 
Mucorini, and, on the other, that true conidia may occur in the same species with 
sporangia. Whilst thus proving the incorrectness of the conclusions of the distinguished 
observers just named, the present observations afford a means of reconciling the appa- 
, rently conflicting results upon which these conclusions, are founded. They do so by 
showing that although the observations of MM. Brefeld, Van Tieghem, and Le Monnier 
may have been correct, their conclusions are not so, merely because of the assumption 
that all the phenomena presented by the species under observation had presented them- 
Selves to each observer. M. Brefeld, because he never encountered any but a conidial 
form of asexual fructification in Chetocladium and Piptocephalis, assumes that sporangia * 
"never are produced in these genera ; whilst MM. Van Tieghem and Le Monnier, believing ` 
