QUARTERLY CHRONICLE. 89 
the changes undergone by each part through the pupa to the 
imago stage. The little air-sacs which are so noticeable in 
the Corethra-larve are, Professor Weismann considers, to be 
regarded as a hydrostatic apparatus rather than respiratory. 
The type of metamorphosis presented by Corethra is con- 
trasted with that presented by Musca, and is thus briefly 
stated :—The segments of the larva are changed directly into 
the corresponding segments of the body of the imago; the 
appendages of the head are changed into those corresponding 
in the head of the imago; those of the thorax commence at 
the last larva-moulting as outgrowths of the hypodermis 
round a nerve or a trachea, from which cellular integument 
the formation of the tissues in the interior of the appendage 
proceeds. The larval muscles of the abdominal segments 
remain unchanged in the imago; the peculiar thoracic muscles 
of the imago, as also some further abdominal muscles, are 
developed in the last larval period from indifferent cell-strings 
already sketched out in the egg. The genital glands date from 
the embryo, and develop steadily ; all other systems of organs 
pass without any or with little change to the imago. Not 
any or only an insignificant corpus adiposum exists. The 
‘pupa state is short, and presents an active life. 
4, “ Researches on the Embryology of the Hemiptera,” by 
El. Mecznikow.—This is the record of some observations on 
the ova of various insects, made in the laboratory of Professor 
Leuckart at Giessen. The genera studied were Corisca, Coccus, 
Aspidiotus, Chermes, and others; also Phryganea and Simulia. 
The author combats Professor Huxley’s view with respect to 
the rudimentary abdomen of Aphis. 
Max Schultze’s Archiv fur Mikroskopische Anatomie. Fourth 
Part, 1865.—The concluding number of the first volume of 
this valuable journal has at last made its appearance, and 
a very beautiful number it is, with eight plates, excellently 
executed, and much interesting matter in the form of original 
papers. 
1. “On the Spermatozoa and their Development,” by F. 
Schweigger-Seidel.—This is a somewhat extensive essay on 
the subject, the author reviewing the work of his predecessors 
in this field, and remarking on the development of the 
spermatozoa in the frog, newt, barn-door fowl, finches, and 
various mammalia. He finally states his results as follows : 
—1l. The spermatozoon is not a simple nucleus structure 
(KG6lliker), but answers to a whole cell. The spermatozoa 
are modified flagelliferous cells. 2. In accordance with this, 
the spermatozoon is developed, not, as Kolhker makes out, in 
the inside of a cell. Cells with spiral rolled-up sperm-threads 
