Davis . — The Fei r tilization of B a trac ho sperm u m . 53 
matic objective with compensation ocular No. 12 (magnification 
750 diameters) even in ordinary work, and relied upon a Leitz 
T2 oil immersion lens for the more minute observations. 
The paper is so divided that the accounts of the three 
species contain but a bare statement of facts ; the consideration 
of the bearing of the results upon the present accepted view of 
the structure and fertilization of the procarp in the genus 
being reserved for the concluding portion of the paper. 
Batrachospermum Moniliforme, Roth. 
The plant which we have identified as a winter-form of 
B. moniliforme , grew very abundantly in a quietly-flowing 
mill-race, covering the stones and dead branches along the 
sides and bottom of the stream with a thick growth an inch 
or more in height. The plant matures in mid-winter, and is 
then almost the sole living occupant of the stream. The 
material from which the figures are drawn was gathered in 
February, when the plant was at its best. 
The trichogynes are club-shaped structures at the ends of 
short branches, which extend usually about half the distance 
from the central axis of the plant to the periphery. At the 
outset it was immediately apparent that each trichogyne was 
not merely a swollen prolongation of a cell, the carpo- 
gonium 1 , which contained the nucleus. There was not only 
a distinct nucleus in the carpogonium, but also an unmistak- 
able nucleus in the trichogyne, staining with haematoxylin as 
a dark blue body, quite homogeneous in structure. The 
1 It has been a serious question to the writer what nomenclature of the organs of 
fructification in Batrachospermum he should adopt. The term carpogonium was 
applied by Schmitz (Untersuchungen fiber die Befruchtung der Florideen) to 
a particular cell because of its resemblance to the oogonium of certain Chloro- 
phyceae, notably Coleochaete. The trichogyne was considered as an extension 
of this cell specialized for the reception of the antherozoid. The writer’s observa- 
tions have led him to a different view of the structure of the trichogyne, but to 
avoid confusion he has used the term carpogonium in the strict sense suggested by 
Schmitz, applying it to the particular cell that bears the trichogyne and gives 
rise to the fertile filaments, the trichophore in the terminology of Bornet and 
Thuret. 
