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CHAPTER V.—COMPARATIVE REVIEW.-—ASCOMFCETES. 255 
important point here, the tendency to the reproduction of like forms, is not the less 
manifest. 
Similar relationships appear to exist in Pleospora herbarum (or Gibelli’s P. 
Alternariae), but I cannot speak decidedly respecting them. By corresponding 
relationships I should now be inclined to explain the facts, observed by myself 
in connection with the reproduction of like forms in the gonidial form of Cor- 
dyceps known as Isaria farinosa!, which led to a controversy respecting its con- 
nection with the cycle of development of Cordyceps militaris, for which Tulasne 
contended. 
Moreover it must easily happen, that in species which show the tendency in 
question, this tendency and the external conditions work together in the same 
direction, and the possible consequences of this co-operation can be readily con-. 
ceived. The long-continued effect of the combined conditions might ultimately result 
“in the permanent separation of the originally connected forms, each preserving its 
existence as a species. This means that each loses the other out of its cycle of 
development, whether the other continues a separate existence or for any reason dis- 
appears. It is quite conceivable that species of Ascomycetes producing gonidia only 
like those described above might originate in this way, 
On the other hand, we have to consider that the two sets of causes determining 
the production of forms in these Fungi, the external and the internal, also work in 
opposite directions, and that the external causes may eventually overcome the internal 
tendency and lead to the reproduction of the other form from the one first produced. 
We may also imagine a przorz that there are cases in which special conditions must 
combine to produce this result, cases in which the few observations that we possess 
do not acquaint us with the real conditions, though they are perhaps very simple. 
Ten experiments may be made with a similar result under different conditions, and 
the eleventh may all at once give a totally different result. Experiences of this kind 
are quite common in this portion of the field of research. These facts admonish us 
to be cautious, and require that the suggestions in the text should once more be 
expressly declared to be only very guarded conjectures. 
Section LXXIV. No less caution is advisable in determining some of the 
organs which have been described above as doubtful, and we must say a word 
more about them in this place. The attempt has more than once been made to remove 
the doubt which exists as to their real nature by declaring them to be rudimentary 
(rudimentär). It will be well therefore to remember that organs or members are 
said to be rudimentary which do not reach the height of development attained by their 
homologues but are stunted in their growth, that is, remain stationary at a stage in 
their development in which they are in every respect immature; such are the 
rudimentary stamens of Salvia and of some diclinous flowers. It is true that the term 
rudimentary has been used in another sense, when an organ is highly developed, 
but is not properly adapted to the function usually discharged by its homologues, 
being applied to some other purpose through a necessity resulting from its high 
organisation, as, for instance, the median staminode of Cypripedium. In some cases 
this mode of expression may be obvious and therefore admissible, especially as there 

1 Bot. Ztg. 1867, 1869. 
