Tue Microscope. “109 
mosing condition. Soon scattered nuclei, derived from the con- 
nective tissue, appear at the sides of these filaments. These 
are next surrounded by protoplasm, and finally they surround 
the nerve filaments, and then, elongating, give rise to the medul- 
lary sheath. Ranvier, some years ago, showed that the sheath 
was probably mesodermic in origin, but it was left for K6élliker 
actually to demonstrate the fact and to show that the ‘nodes’ 
actually represent the limits of the investing cells. This paper 
is also important from the fact that it shows that all nerves are 
outgrowths from the neural cord and do not pre-exist in the con- 
nective tissue in an undifferentiated condition. 
Taste in Insects —F. Will has recently investigated both 
experimentally and histologically the organs of taste in insects. 
The organs are found on the tongue and mouth parts, and con- 
sist of numerous cells each with its nerve supply and each, like 
all sense organs (except eyes) of Arthropods, terminating in a 
bristle. A detailed account would not be intelligible without 
numerous illustrations. The experimental proof that these are 
really organs of taste is conclusive. Among other tests, the 
author accustomed wasps to coming for sugar and then replaced 
this with alum. This they tasted of but immediately retreated, 
and with the “drollest motions” tried to clean their tongue with 
the feet. Other experiments, conducted under the compound 
microscope, were even more conclusive. The article will be 
found in the Zeitschr. wiss. Zool. xlii, y. 674, 1885. 
Development of the Ascidians—-Van Beneden and Julin 
have three papers on the development of the Ascidians in the 
volumes for 1884 (vols. vii and viii) of the Bulletin of the Royal 
Academy of Belgium. One details the relations of the nervous 
system of the adult with that of the larva; the second describes 
the manner of formation of the branchial aperture and the clo- 
aca; while the third is concerned with segmentation and gastru- 
lation. It contains a complete genealogy of the cells from the 
egg until segmentation results in forty-four cells. The authors 
claim that with the first division the right and left halves of the 
animal are distinguished; the second segmentation separates 
the anterior and posterior cells, etc., the steps of development 
taking a mathematical character, until at the formation of the 
gastrula the authors claim to be able to point out exactly what 
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