[Vor. 1 
38 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
in the light. While in a few cases bacterial colonies developed 
about the zygopsores, it was found that the great majority 
were free from all adhering bacteria. Such zygospores as were 
bacteria free were then transferred to test tubes containing 
sterilized mud and pond water. Although about sixty such 
transfers were made, not a single one yielded a growing culture, 
although zygospores kept in battery jars in the laboratory 
showed а high percentage of germination. It will require 
further experiments to find a suitable medium for the germina- 
tion and subsequent growth of isolated zygospores. However, 
the isolation of bacteria-free zygospores justifies the opinion 
that with them it will, sooner or later, be possible to culture 
Spirogyra in a state of purity. 
HETEROKONT/E 
Botrydium granulatum (1.) Greville.—This form is, in its 
general morphology, so similar to Protosiphon, that the tech- 
nique, as regards the use of chlamydospores, described for the 
latter, is entirely applicable here. Botrydium when submerged, 
however, forms an abundance of zoóspores instead of gametes, 
and from these pure cultures can be obtained with great ease 
when plated in the usual manner. Тһе method for using the 
chlamydospores can also be considerably abbreviated in Botryd- 
ium. When the plants form chlamydospores, the aerial 
globular portion of the plant collapses. Тһе cell, however, is 
so large that the aerial bag сап be torn open with fine sterile 
forceps, the spores removed under a hand lens with a needle 
and transferred directly to liquid agar. Platings made in this 
way show a very slight bacterial contamination, and pure 
transfers сап be made in abundance. While a direct, bacteria- 
free transfer has not been thus effected, it is altogether probable 
that it ean be done. Тһе pure transfers of Botrydium having 
been obtained, it was found that their development on agar 
was extremely slow, and ultimately all of the cultures died. 
Further experiments will be necessary in order to provide а 
favorable medium for growth. The clay-cup evaporimeter 
may perhaps prove of service in this connection as it did in 
the case of Pleurococcus. 
Botrydiopsis sp.—' This form was found abundantly during 
