1893. ] The Roots of Ranunculaceae. 101 
development of the central cylinder and a corresponding de- 
crease of the cortex region. This change is partly brought 
about by the increase of conjunctive parenchyma in the cen- 
tral cylinder, the xylem being all collected at the center and 
the phloem in several scattered rays radiating from this 
center. But the decrease in the cortex region of the oldest 
roots is mainly due to exfoliation, the epidermis and in some 
cases all but two rows of the cortex cells being thrown off, so 
that the endodermis, consisting of many very small regular 
cells whose walls are generally cutinized, now serves the pur- 
pose of anepidermis. This exfoliation was especially noted 
inthe Thalictrums studied. In this type are placed but four 
of the plants that came under m study, viz.: Thalictrum 
aioicum, T. polygamum, Anemonella thalictroides and Aquil- 
gia Canadensis, 
2. Meristem of vegetative potnt. 
e ko found that the roots of the Ranunculacee do not all 
es €r one type of apical meristem structure, but that there 
WO main types and a possible subsidiary type to be recog- 
nized in these roots. 
scsehigay ee having a distinct plerome and periblem and a 
Resenculy: Progen. _ In this type I have placed 
Meth. ci. € “aes R. circinatus, R. aguatilis var. tricho- 
Vetcicalans: oe . Serene and probably R. repens, R. 
_ Subsidiary SAY espa Site 
Wm distinct. ia: € the hrst type except that the epidermis 
though itis bs Ag entirely about the vegetative point, 
initial gro § Dirth to the root-cap and so having the same 
Q Ups as the first type. Here are included but two 
