74 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Chromosomes of Conocephalum conicum.— Amos M. Showalter 
( Bot . Gaz ., 1921, 72, 245-9, 2 pis.). A study of sex potentialities 
in chromsomes. It has been claimed that two spores out of every tetrad 
in Sphserocarpos and Thallocarpus produce male plants, and the other 
two yield female plants. In several dioecious mosses also the sex 
potentialities are probably separated during the reduction divisions. 
As yet a visible chromosome difference between the sexes has been 
found only in two plants, both of them species of Sphserocarpos. The 
results are negative in Conocephalum ; but the author finds : (1) The 
chromosome number in the gametophyte is nine instead of eight as 
reported by previous investigators. (2) The chromosomes vary 
considerably in size, one being very much smaller than any of the other 
eight. (3) There is no perceptible difference between the chromosomes 
of the male and those of the female plant. (4) The plants received 
from Ithaca and Copenhagen show the same number and size relations 
of the chromosomes as do the Wisconsin plants. A. G. 
The Liverworts of Somerset.— W. Watson (, Somersetshire Archseo- 
logical and Nat. Hist. Soc., 1920, 66, pt. 2, 134-59, figs.). A list of 
102 species of Hepaticae and numerous varieties and forms, with some 
notes interspersed. The distribution within the county of Somerset is 
given, together with the authority for each record. A comparison is 
made with the neighbouring counties of Devon and Gloucestershire. 
A. G. 
Thallophyta. 
Algae. 
Physiological Researches on Green Algae grown in pure Cultures. — 
H. Kufferath (Bull. Soc. Roy. Bot. Belg., 1921, 54, 49-77, 78-102). 
In Part I. the author discusses shortly the action of strongly concen- 
trated gelatine on species of Bacteria, and then gives the results of his 
experiments with the same medium on algae, varying the concentration 
between 15 and 70 p.c. Morphological details of each culture are given, 
according to the various percentages of concentration. Certain species 
will grow in any concentration, but development is better and more 
abundant in the less strong ones. Species of Hormidium , Stichococcus 
lacustris Chod., Ghlamydomonas intermedia Chod., and Ghlorococcum 
viscosum Chod. hardly grow at all in concentrations exceeding 25 p.c. 
or 30 p.c. It is found that in all species except Stichococcus a propor- 
tionate increase of cell-dimensions takes place, corresponding with the 
increase in concentration of gelatine. A reduction of growth takes 
place, in proportion to the lack of water in the gelatine, except in 
the case of algae whose natural habitat is more or less dry. Sporulation, 
which is normal and active in weak concentrations, ceases in strong ones. 
Reduction of cell-division takes place. In Part II. the author describes 
his researches into the action of various osmotic substances on Ghlorella 
luteo-viridis and Hormidium lubricum. Finally, in his conclusions, he 
sums up the results in general. As regards the action of osmotic inor- 
ganic salts, the author confirms previous researches in so far that in 
the case of a combination of osmotic salts each salt acts independently, 
