1885.] Botany. 801 
to form free passages between the conjugating cells, and through 
these the protoplasm passes from the one cell to the other, result- 
ing in the formation of a resting spore (zygospore). In Meso- 
carpus the process 
differs in this that 
the protoplasm from ` 
both the conjugating 
cells passes into the 
connecting tube and 
there forms a rest- 
ing spore is thus 
inter-filar, while in 
the former it is intra- 
ar. 
The two plants 
crossing, as shown 
in the figure. Near 
the point of crossing 
each plant sent out 
a characteristic con- , 
jugating tube. The Fic. 1.—a, plant of Spirogyra i - 
tube from the Spiro- Mesocarpus eters ee A be. ae ty ; Nei 
gyra was bent up Spirogyra; d, conjugating tube sent out by Mes ; 
and partly around %3 dead cell of the Spirogyra plant containing parasites _ 
the filament of Mes (Iridium sp). 
socarpus, while the tube of the Mesocarpus had pushed out 
inst the Spirogyra filament with such force as to indent the 
latter very greatly. 
The attempt at fertilization was futile, of course, and so no 
effort was made to keep the specimen alive. It was preserved in 
camphorated water and mounted upon a slide for further study 
and inspection. 
We have in this case a suggestion of a reciprocal influence 
exerted by one cell upon another in process of conjugation. 
It is probably a kind of sensibility to contact—an irritability, as the 
older vegetable physiologists would have called it. There was cer- 
tainly a response to some influence on the part of one or other of 
ese plants in the case before us. It is perhaps impossible to deter- 
mine which plant took the initiative, whether the tube of Meso- 
carpus or of Spirogyra was first pushed out, but it is impossible 
to escape the conclusion that the second tube was pushed out in 
response to the first. It is possible that the first tube may have 
originally pushed out towards a filament of its own kind, and be- 
coming displaced may have continued its growth towards the 
