
1891.] Embryology 3 919 
ately upon the fission of the worm. They are present in great num- 
bers in the Naids, where the formation of new tissue is much more 
rapid than in Lumbriculus, and also in Tubifex, in which regeneration 
is a very slow process.” 
Neuroblasts in the Arthropod Embryo.‘—Mr. William M. 
Wheeler publishes a short paper on the discovery of neuroblasts or 
formative ganglion cells in Arthropods. ‘‘ Carefully made transverse 
sections through either lateral chord are seen to consist, in early stages, 
of two kinds of ectoderm elements: smaller ones with rather deeply 
stainable elongate oval nuclei, and four large succulent cells with pale 
spherical nuclei. These four large cells, the neuroblasts, lie side by 
side just beneath the smaller ectoderm elements in a plane parallel to 
the surface of the yolk.’’ The author believes the eight rows of the 
lateral chords to be homologous with the two rows of cells derived from 
the neuroteloblasts of Annelids, and ‘‘ the fact that there are two rows 
in an Annelid, whereas there are eight in Xiphidium, can constitute on 
very serious obstacle to this homology.’’ The neuroblasts have been 
seen in Xiphidium, Melanoplus, Blatta, and Dolyphora. 
Morphological Notes from the Biological Laboratory of _ 
the Johns Hopkins University.—The anatomical and embryo- 
logical work done in the morphological laboratory of Professor Brooks 
is published annually, in the form of complete papers and preliminary 
notes, in the University Circular? 
The May (1891) number contains the following embryological 
articles : 
‘ On the Structure and Development of the Gonophores of a Certain 
Siphonophore Belonging to the Order Auronectz Haeckel.” By W. W. 
Brooks and E. G. Conklin. 
“ Preliminary Note on the Embryology of Crepidula fornicata and 
Urosalpinx cinerea.’ By E. G. Conklin. 
“The Anatomy and Transformation of Tornaria: A Preliminary 
Note.” By T. H. Morgan 
‘ Note#on the Habits ind Larval Stages of the American Lobster,” 
By F. H. Herrick, of Adelbert College. 
ine E Organs and Early Stages of Development of 
the American Lobster.” By F. H. Herrick, of Adelbert College. 
“ On the Early ek of Echinoderms.” By W. H. Brooks, 
4 Journal Morphology, Vol. IV., No. 3, 1891. 
5 Vol. X., No. 88, May, 189r. 
Nat.—October.—s. 
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