294 The Botanical Gazette. 
Observations on the zoospores of Draparnaliia. 
L. N. JOHNSON. 
WITH PLATE XXXII. 
Having been interested during the past season in studying 
various algz I have been surprised at the lack of accurate de- q 
scriptions of the zoospores and their mode of formation. 7 
Aside from the familiar papers on Ulothrix zonata little seems — 
available, beyond scattered references in various text books. i 
The plant selected for special study was Draparnaldia pl 
mosa Ag. Concerning this genus little information canbe 
gleaned from the accessible books. The accounts by the older 
writers are chiefly interesting historically. For instance De 
caisne! in 1842 spoke briefly of the zoospores, and figures 
them though with no attempt at detail. He says that he 
failed to see any motion of them either before or alter e 
escape from the cell. It is possible that he saw only rest 
spores. a 
Kuetzing, in his ‘‘Metamorphose des vegetaux spp : 
mentions finding Draparnaldia producing zoospores tiled 
occasion, but lost the material before making any de ia 
study of them. He speaks with regret of thus failing or ; 
the opportunity to investigate the vexed question ow) 
zoospores were really animals. Before this Treviranus © 
observed the zoospores and shown that from them get 
plants of Draparnaldia. ; 
_ Derbes and Solier, in a paper published 1 
brief but concise account of the zoospores 10 
lated Stigeoclonium tenue Kg. 
n 1850,° gave" 
the closely * 
least to-the average botanist. This being 5° . at of 
thought desirable to give a somewhat minute ies 
structure and formation of the zoospores 1m the spec 
tioned. 
The form of the plant is probably ig made 
ist. The main axis is comparatively stout, oi Ils tined bY 
of cylindrical or barrel shaped cells, with the wa 3 
des Sc. Nat - 
familiar to every gel 
1Essai sur une classification des algues, etc. Annales 
XVII. 314. 
*Annales des Sc. Nat: Bot. II. x1. 136. 
Bot. Il. ™ 
*Organes reproducteurs des algues. Ann. : 
des Sc. Nat. 
