ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
715 
first signs of segmentation. The author cannot confirm the statement 
of Cholodkovsky that the genital cells have their origin from yolk- 
cells. 
When the first sexual differences become apparent, the genital rudi- 
ment of the female consists of a right and a left elongated cord of cells 
which, even in the embryonic period, becomes converted into numerous 
separate ovarian tubes. The almost universally accepted doctrine that 
epithelial cells and eggs are only modifications of primitively similar 
elements is not true of Phyllodromia. While the genital rudiment of 
the female is completely converted into the ovary, that of the male is 
only partly converted into the testis. At the time when sexual dif- 
ferentiation commences, the male rudiment consists of cord-like struc- 
tures which extend, right and left, from the second to the fifth abdominal 
segment. Each genital rudiment consists of genital and epithelial cells ; 
the greater number of the latter have the form of elongated cells on the 
ventral side of the rudiment, and form the anterior widened part of the 
vas deferens. The genital cells are not regularly distributed within 
the rudiment, but are collected into larger numbers at four points. 
These are the first signs of the four testicular follicles of which the 
gonad of either side consists. Part of the genital rudiment is now seen 
to consist of the four follicles which are directly connected with the 
elongated cells that form part of the vas deferens, in a ventral direction 
only. They have, therefore, no connection with the terminal plate. The 
second part of the rudimentary gonad consists of those genital and 
epithelial cells which have not taken part in forming the testicular 
follicles, and they are directly connected with the terminal plate. By 
the contraction of the efferent duct the testicular follicles become to 
some extent pushed out from the genital rudiment and lie below and 
behind it. That part of the genital rudiment of the male which is not 
used in forming the testicular follicles may be seen to represent the 
rudiments of a female gonad; in some cases this is developed so far 
that both egg-tubes and separate ova become developed ; but this female 
organ has no direct connection with an efferent canal. The presence of 
this arrangement in so archaic a form seems to prove that the ancestors 
of insects were hermaphrodite. 
Respiration of Decticus verrucivorus.* — M. C. Contejean has studied 
the mode of respiration of this Grasshopper. He finds that the abdomen 
alone effects the respiratory movements. Inspiration is passive and is 
due to the elasticity of the parts of the exoskeleton and to the reaction 
of the viscera. Expiration is active and lasts longer than inspiration. 
The respiratory movements increase in frequency with the activity of 
the animal, and their number is increased by the heat and irritability 
of the insect. Removal of the head does not put a stop to respiration, 
the rhythm of which is scarcely slowed. If the abdomen is divided 
into several parts, each breathes separately. From the experiments 
made by the author on the influence of the nervous system, he is led to 
conclude that the lower part of the cord is not sensory and the upper 
part motor as Faivre has demonstrated for Dytiscus. This would show 
that the organization of the Orthoptera is less elevated than that of the 
* Comptes Rendus, cxi. (1890) pp. 361-3. 
