1002 General Notes. [ December, 
the literature of this department of botany. Why cannot some 
of our publishers secure the translation of this work? The 
late Professor Parlatore, before his death, had planned a work on 
the Comparative Anatomy of Aquatic Plants, which unfortu- 
nately was left unfinished. The fragmentary work consisting of 
nine fine plates showing figures of cross and longitudinal sec- 
tions of different organs, together with explanatory text, has been 
published in Florence under the title of Zavole per una “ Ana- 
tomia della piante acquatiche.’ Species of Alisma, Callitriche, 
Ceratophyllum, Hippuris, Myriophyllum, Naias, Nelumbium, Nu- 
phar, Nymphea, Potamogeton, Trapa, Vallisneria. Victoria, and 
many other phanerogams, and of J/series, Marsilia and Pilularia 
Dr. 
ery tissue of others. Even collenchyma may serve as a Con- 
ducting tissue. Mature vessels (tracheary) conduct no sap, and 
parenchyma does so only when sap is exceedingly abundant. 
ZOOLOGY. 
Tue Caroma Turory—Since Haeckel’s publication of his 
Gastraea theory, the most important generalization in embryology 
is the Cceloma theory of the brothers Hertwig.1 It is an expres 
sion of the history of the nature and changes of the middle layer 
of the blastoderm. 
They define two types of middle layer as foliows : In the ex 
it is formed of separate cells which wander from the epiblast an 
hypoblast, which in some instances appear round the mouth of the 
this form they restrict the name mesoblast. Moreover 10 the 
animals which present the mesenchym, there is a cavi 
the epiblast and hypoblast, which is not the true 
Such are the Plathelminths (flat worms) Bryozoa and Mollusca. 
To this series they give the name of Pseudocalia. 
oderms, brachiopods, round worms, arthropods and vertebrates 
possess a mesoblast. Here the two layers of the mesoblast me 
rate and form the walls of the body cavity, which is divided y 
name of the Enterocelia. Animals are thus divided into tWO 
divisions, those in which the blastoderm consists of two 
and those in which it is formed of four layers. ‘ a 
a The consequences of these modes of origin are seen 1n chara¢ 
cD * Jenaische Medicinische Zeitung. 1881, 
ity between o 
