54 
Peirce. — A Contribution to the 
santhemum ; and C. glomerata , Choisy, on Impatiens Sultani , 
Hook., /. Balsamina , L., and /. parviflor a , DC., &c. Of these 
the two larger, C. europaea and U. glomerata , proved most con- 
venient for experimental purposes, owing to their own greater 
vitality, and also to the fact that their host-plants (except 
Ur tied) bear confinement in a rather dry greenhouse very 
well. C. glomerata , an American species, is decidedly better 
for indoor study than C. europaea , attaining under such con- 
ditions a larger size than the latter, though differing from it 
in this respect only slightly out of doors ; and the translucent 
character of its hosts, their large-celled pith and cortex 
(especially of I. Balsamina ) make it an almost ideal plant for 
histological as well as physiological observation. 
I began my experiments late in April, and continued them, 
without interruption, until the middle of August. Some of 
the material was raised from seed in the comparatively dry, 
at times cool, at times very hot, greenhouse which forms part 
of the botanical laboratory of the University of Leipzig. 
More of it was cultivated in the Botanic Garden : host and 
parasite were sown or planted together in pots in a frame, 
and when the hosts had become a few centimetres high, and 
the Cuscuta-seedlings had become well attached to them, the 
clumps of soil enclosing the roots were removed undisturbed 
from the pots and set into a warm, not too sunny, well- 
watered bed. Still more was sown with the seeds of the hosts, 
quite without precautions in dry and sunny, or in somewhat 
moist and shady, places. The rest of the material was taken 
by transfer (as will be described further on) from an unpotted 
to a potted host, and brought into the small greenhouse 
above referred to. Owing to the unusual dryness of the 
season, accompanied in May and June by longer or shorter 
periods of abnormal coolness, the plants out of doors were 
not so luxuriant, and did not so long vegetate, as in more 
favourable seasons, but came sooner and more compactly into 
□loom. As will be shown further on, these differences from 
the usual conditions have made clearer some interesting facts 
which otherwise might have escaped my notice. 
