1913] OSTERHOUT—PROTOPLASMIC CONTRACTIONS 447 
glass slide with a circular opening (15 mm. in diameter) into which 
is fitted a glass cylinder (¢c) 12 mm. high upon which is cemented a 
glass disc (d) ; surrounding 
this is another cylinder, 
the width of the space 
between the two being 
about 1 mm.; a part of 
this space is filled with 
paraffin (e). The outer 
cylinder is pierced on 
' both sides by small glass 
tubes (0, 6). The outer 
cylinder projects above 
the inner so that when 
the cover glass (f) is in 
place the width of the 
space between (d) and (/ ) Fic. 1.—Sectional views of irrigation cham- 
is a little less than 1 mm. ber: a, slide; }, inlet and outlet tubes; c, glass 
It is necessary to have cylinder; d, glass plate; f, cover glass (upper line) 
: : sr material (lower line). 
this space narrow, since 
otherwise when introducing a solution of greater specific gravity 
than the one with which the chamber is filled, the new solution 
may flow over the bottom of the space without coming into contact 
with the plants, which are fastened to the under side of the cover 
glass. The paraffin (e) extends 
downward to the slide; the 
liquid is in consequence obliged 
to pass upward through the 
space between (d) and (/) 
before it can flow out at the 
opposite side, and it must 
Fic. 2.—Material in irrigation cham-~ therefore bathe the plants 
ber: ¢, glass cylinder; f, cover glass; & which are attached to the - 
material; 4, bits of cover glass; 7, vaseline. 
—Sectional view. cover glass (f). 
The attachment is made in 
the manner shown in fig. 2. The plant is first fastened to the cover 
glass (f) by vaseline (i, indicated by the dotted area) and a drop 
ba 
