PROGRESS OF MICROSCOPICAL SCIENCE. 97 
periphery, and then the membrane is shown very distinctly. The 
grains of the plasma are of two kinds:—1. Strongly refringent, with- 
out a well-defined bounding circle; these are merely compacted 
masses of the plasma. 2. The ordinary sulphur-grains resemble oil- 
drops, and are surrounded by a dark circle. The only form of mul- 
tiplication observed was by division. Moreover, the “ zooglea” state 
was never seen in salt-water infusions. 
Ganglion-cells in the Heart of the Crawfish—A paper has been 
read on this subject recently before the Royal Academy of Sciences at 
Vienna, by Herr Emil Berger. However, as merely the title is given 
in the weekly reports of the ‘ Academy,’ we merely announce the fact 
of its publication. 
The Seaual Organs of Squilla mantis—This subject, similarly to 
the preceding one, has had a communication on it read before the 
Royal Academy of Sciences at Vienna, but merely the title is given 
in the ‘ Proceedings.’ The author of the memoir was Herr Carl 
Grobben. 
Dr. Braithwaite’s Book on British Sphagnacee.—Dr. Braithwaite 
announces the intended issue to subscribers of ‘ Sphagnacez Britannic 
exsiccate,’ which will include about fifty forms, illustrating his recent 
monograph, in the choicest dried specimens, both mounted and loose 
for microscopic examination. Three Continental species not found in 
Britain will also be included. Only fifty copies will be prepared, 
in imperial quarto size, price 25s., and the author will be glad to have 
the names of those desiring to possess the work. Address, The Ferns, 
Clapham Rise, London. 
Eriksson on the Dicotyledonous Root.—The December number of 
the ‘Journal of Botany, quoting from the ‘ Botanische Zeitung,’ says 
that Herr Eriksson’s views on the above subject differ from those of 
Herr Holle, which the ‘ Journal of Botany’ gives at some length. It 
says that he admits four types of structure:—1. The root-end has 
three separate Meristem-tissues, of which the Plerom gives origin to 
pericambium, fibro-vascular bundles, and pith; the Periblem acts as 
the Meristem of the primary bark-layers, and the Dermatogen or 
Dermatokalyptrogen produces the epidermis and root-tip (Haube). 
The Periblem of this type arises either from a single cell-row 
(Initialenreihe), or from two or from three or more cell-rows. 
2. Two Meristem-tissues are present in the root-end ; a Plerom and 
a single tissue for the production of primary bark-layers, epidermis, 
and root-tip. 38. Only a single Meristem-tissue is found. 4. This 
shows Plerom and Periblem, but the latter is external, and builds up 
the root-tip from without inwards. Numerous instances of the 
occurrence of each type are given, and a fuller treatment is pro- 
mised at some future time. 
The Ambiguous Position of the Monads.—We have additional dis- 
coveries regarding the nature of monads by the Russian naturalist, 
Cienkowski. These organisms are on the border-land of the plant 
world, and in some cases form protoplasmic nets (plasmodia) like the 
