1911] SHREVE—JAMAICAN HYMENOPHYLLACEAE 205 
cans frequently observed in the field was found to be due to a retreat 
of a large proportion of the chloroplasts to the lateral walls of the 
cells, a performance that was afterward noticed in experiments 
with this and other species when isolated leaves were surface- 
dried and kept without access of water in a moist chamber, and also 
in rooted plants of Trichomanes rigidum which were dry as to the 
leaves. On the presumption that illumination was the principal 
factor involved in the movement of the chloroplasts, plants of sev- 
eral species were placed in bright diffuse light and in direct sunlight, 
F 1G. 7.—Vertical section of the leaf of Trichomanes Hookeri, to show the distri- 
bution of the chloroplasts and the size of the sap vacuole in a non-specialized form; ~ 
X 764. 
the fronds being kept quite wet in the first instance by keeping the 
plants under a bell jar, and in the second case by submerging 
them. The species used were Trichomanes radicans, T. crispum, T. 
rigidum, T. capillaceum, Hymenophyllum sericeum, and H. hirsutum. 
The first of these was the only species influenced. Under bright 
diffuse light for 2 hours, about one-third of the chloroplasts had 
gone to the lateral walls, and illumination for 4 hours sent one-half 
of them there. The influence of full sunlight was nearly identical. 
When all of the above-named species were placed in total darkness 
for 20 hours, the chloroplasts were found in their normal positions 
on the outside walls. 
hese tests serve to indicate that intense illumination brings 
about a movement of the chloroplasts only in 7. radicans. Since 
It is found only in heavily shaded habitats, and since species n 
Which there is no responsive movement in strong light are found to 
have a Portion of their chloroplasts on the lateral walls when the 
