Tou^S.ZTriff] PliOGRESS OF MICROSCOPICAL SCIENCE. 273 
making gunpowder, has given an illustration of the practical use of 
the microscope in diagnosing the different forms of stems. He has 
given the characters of the sections (transverse) of different species, 
and has delineated them in a handsome plate. 
The Emhryogeny of Crustacea. — M. Edouard Van Beneden continues 
his inquiries on this interesting subject. In his last memoir, which 
he has reprinted from Bulletin de VAcademie Boyale des Sciences of 
Belgium, No. 8, 1869, he deals with the development of Mysis, 
selecting M. ferruginea as a type. A 4to plate contains several 
figures illustrating the different phases of the ovum, from the time 
when the embryonical development has hardly begun, up to the date 
when it has undergone all the development that takes place within 
the egg. He thus sums up his conclusions : — (1) The blastoderm 
is formed in the course of a partial segmentation of the vitellus. (2) 
The cellular zone, which results from the multiplication by division 
of the cicatricule, extends itself over the whole surface of the egg, to 
form a closed blastodermic vesicle, before any trace of organs is seen. 
(3) The division of the embryo into a cephalic and a caudal lobe 
results from the division into two laminae of a primordial cellular fold, 
which may be compared to the cellular column [Keimhiigel] of 
Hemiptera, Orthoptera, and Lepidoptera. The identity of formation 
of these organs, which have evidently the same morphologic value, and 
the perfect analogy between the phenomena which subsequently take 
place in the cephalic lobe in the cmstacea on the one hand and the 
insects on the other, are in my opinion facts which enable us to 
determine with ease and certainty what are the homologous organs in 
these two groups of Arthropoda. (4) The caudal appendage of 
Mysis is folded under the abdomen as in all Decapods. (5) The 
caudal lobe commences to be formed before it is possible to recognize 
the least trace of antennary appendages ; these appear at the same 
time as the mandibles in the form of simple cellular papillae. (6) 
The Nauplian cuticle is formed at once over all the surface of the 
€mbryo ; it is the first embryonic cuticle. Mysis does not undergo 
a blastodermic moult. (7) The tail, which is bifid in some species 
(M. vulgaris and M. cJiameleo), is simple, and terminates in a cul-de-sac 
in other species [M. ferruginea). 
Begeneration of the Spinal Cord. — In a recent series of researches 
on frogs, MM. Masius and Vanlair have arrived at certain conclusions, 
which are thus expressed by M. Th. Schwann in his report to the 
Belgian Academy. (1) The spinal cord in the frog repairs the 
destroyed tissue by means of a new medullary tissue. (2) The return 
of the functions which had been previously suspended coincides with 
this repair ; and (3) In reproducing the structure, cells precede fibres 
in course of development. — Bulletin de VAcademie Boyale de Belgique, 
No. 7. 1869. 
The Development of the Crystalline Lens. — M. Woinow, of Moscow, 
recently presented a memoir on this subject to the Vienna Academy 
of Science. It has not yet been published in full. — L' Institute Oct. 13. 
The Structure of the Cerebellum. — Herr Obersteiner publishes a 
VOL. II. U 
