260 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the genus Habronema, and to this genus he now adds a new species, H. 

 mansioni, from the stomach of the buzzard (Buteo). He describes the 

 minute characters of the surface, the spines, the bursa, the ovijector, 

 and the eggs. 



Female Reproductive System of Tropidocerca.* — L. G. Seurat 

 describes this in two species of this peculiar genus. The deformed 

 globular females are found in the walls of the proventriculus of various 

 birds — such as birds of prey, crows, and sparrows. In Tropidocerca 

 inermis there is a greatly elongated very muscular vestibule ; in T.fissi- 

 spina the vestibule is very short and gives off a bursa copulatrix, which 

 receives the sperms. The great difference in the vestibule in the two 

 species is correlated with the very long spines of the male in the first 

 case, and the very short spines in the second. 



Plastochondria in Dividing Ova of Ascaris megalocephala.| — Fr. 

 Meves describes accumulations of plastochondria in the immediate 

 vicinity of the centrosomes, or centrospheres. For the idiosome envelope 

 around the centriole in testicular cells, the term centrotheca is proposed, 

 and it is pointed out that this is not to be regarded as comparable to 

 an attraction sphere. The study of the plastochondria in the Ascaris 

 ovum shows clearly that the centrotheca and the attraction sphere are 

 two quite different things. 



Development of G-ordius aquaticus.}— A. Muhldorf finds that there 

 is total almost equal cleavage. Each blastomere has four chromosomes. 

 A blastula, with a spacious segmentation cavity, is followed by an 

 atypical gastrula. The mesenchyme is formed from both ectoderm and 

 endoderm. The mesenchyme forms " residual mesenchyme-cells," the 

 larval musculature, and two refractive "globules/ 1 The embryo 

 elongates, and a transitory praesomatic portion is distinguishable from a 

 persisting somatic portion. 



A second invagination at the animal pole forms the region of the 

 spines and the proboscis. A club-shaped swelling of the archenteron 

 forms the " brown gland," which comes to be bigger than the gut itself. 

 After it is separated from the archenteron, it communicates with the 

 proboscis. 



The larva is bilateral, symmetrical, and has two anterior ends — 

 represented by the proboscis and the blastopore. Corresponding thereto 

 are two posterior ends. At the " ontogenetic-anatomical " posterior 

 end, there is formed the anterior end of the adult. The prascephalon 

 is very complicated. 



Except the protractors of the proboscis, the musculature is meso- 

 dennic ; there are only longitudinal muscles ; they do not form a 

 continuous layer. There is no trace of metamerism. There is no 

 secondary coeloin, nor cerebral ganglion, nor specific sense-organ. The 

 nervous system is a median thickening. Of the parenchyma, which is 



* C.R. Soc. Biol. Paris, lxxvi. (1914) pp. 173-6 (3 figs.). 



t Arch. Mikr. Anat., lxxxiv. (1914) 2te Abt., pp. 89-110 (2 pis.). 



% Zool. Anzeig., xlii. (1913) pp. 31-6. 



