1891-] Noteworthy Anatomical and Physiological Researches. 17 
pee and the Cycadez and Conifere. sy this connec- 
one can not but deplore that in some quarters American 
otkny has not’ yet freed itself from the slteceiher obsolete 
notion that the Conifer should be placed between the mono- 
cotyledons and the dicotyledons. CONWAY MACMILLAN. 
Effects of parasitism of Ustilago antherarum Fries.! 
Ustilago antherarum is included by Saccardo? under U. vio- 
lacea (Pers.) Fckl. and is well known as parasitic in the anthers 
and ovaries of Silene, Lychnis, Saponaria, Pinguicula, Stel- 
laria and other allied plants. By the growth of the fungus, 
what has been termed by A. Giard ‘‘parasitic castration of 
the anthers” takes place. There is, however, a hypertrophic 
development of the anther and in the diclinous flowers of 
Lychnis, which have in common with other such flowers ru- 
diments of the undeveloped sporangia —this hypertrophy 
suffices to give the flower a monoclinous appearance. Under 
the irritation of the parasite the rudimentary anthers in pistil- 
late Lychnis flowers are stimulated to develop, but the tapetal 
and archesporial layers of the thecz are supplanted by the fun- 
gus mycelium and subsequent growth of spores. For a con- 
siderable time the Ustilago plant develops by a kind of 
symbiosis with the cells of the host. This goes so far that 
the anther walls are, in normally pistillate Lychnis flowers, 
stimulated to form the typical layers by which the ordinary 
dehiscence is brought about. Thus the Ustilago spores are 
scattered from the hypertrophic anthers of Lychnis precisely 
as if they were normal pollen spores. A corresponding and 
attendant atrophy of the pistil will be observed in most cases, 
and it.is the nutritive stream which properly should go to- 
ward the pistil, that is diverted toward the hypertrophic 
anthers. And furthermore the various accessory characters 
of the staminate flower are developed in proper order under 
this parasitic stimulation, so that the normally pistillate but 
apparently staminate flower presents the appearance of pollen- 
bearing to such an extent that it is doubtless visited by those 
insects which habitually transfer pollen from the staminate 
flower to the stigma of the pistillate. Now as the Ustilago 
spores are developed in lieu of pollen spores and make their 
1Vuillemin: Sur les effets du parasitism de I’ Ustilago antherarum, Comptes 
Rendus Hebd. cx. 662. (1891. 
*Sylloge Fungorum vit. 574. 
1. No, 1. 
