332 OTANICAL GAZETTE [OCTOBER 
a drop of water simply, but where they were started in nutritive media, 
whether malt solution or a very small dead insect, in two or three days 
the fungus had penetrated both leaves, the one on which the conidia 
were sown as well as the one from 2—4™™ above it. Organs of attach- 
ment formed freely on the overhanging surface here as in the artificial 
cultures already described, while on the lower surface they were rarely 
met with. Whenever organs of attachment had thus formed tubes 
were sent out from them into the host in the manner described by 
former writers. But that the fungus is not confined to this means of 
entering the host was seen in sections of a leaf on which conidia had 
been sown in a drop of malt solution four days previous to sectioning. 
Here contact with other leaves was impossible, so that the erect 
hyphe bore conidia, while the prostrate ones ran over the surface of 
the leaf until a stoma was found for entrance (fg. 8). Again, some of 
the conidia produced by this mycelium had germinated and sent germ- 
tubes directly into the leaf between the lamelle of two adjacent cells 
(fig. 9). In the latter case the tissue of the leaf was probably weak- 
ened by the presence of the fungus in some other part, since after 
entrance the tissue is rapidly consumed. 
__ From the foregoing experiments, and others not recorded, the writer 
concludes that with this fungus the formation of organs of attachment 
is determined by external conditions which may be artificially produced 
by placing in proximity to the hyphe a hard surface for contact, 
or they may be met with in nature where plants are crowded together 
so that the leaves of different plants lap over each other; that when 
this condition is not present conidiophores will be developed instead 
of organs of attachment ; that in general conidiophores and organs of 
attachment are both physiologically and morphologically equivalents 
that biologically the fungus makes use of the organs of attachment ba 
penetrate a neighboring leaf, or it has the alternative, after starting 
saprophytically, of entering the host either through the stomata or by : 
sending germ tubes directly into the tissue. ae 
The literature of Botrytis vulgaris and allied forms is considerablt e 
yet comparatively little has been said concerning the morphology ° 
the organs of attachment. Brefeld? classes them, on account ee 
manner of attaching themselves to a substratum, with other “Hi 
organen,” while De Bary throws more light on their biological i 
* Schimmelpilze 4: 112. 
5 Bot. Zeit, 44: 382, 412. 1886. 
