ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 959 



On a previous occasion M. Villot has insisted on the homology of the 

 muscular fibres of Gordiiclee and Nematoids ; he has since been able to 

 detect a phase in the development of the muscular fibre of Gordius in 

 which it is for a time in the stage in which those of Nematoids are 

 permanently ; the fibrillar substance only invests part of the inner wall of 

 the embryonic cell, and the as yet unchanged portion is represented by a 

 vesicular enlargement which is adherent to the parenchyma. 



Some additions are made to our knowledge of the interesting phenomenon 

 of the retrogression of the digestive tube, and it is found that what has 

 been hitherto taken for the mouth of young Gordii is really an invaginated 

 proboscis ; it is the rostrum of the embryo which j)ersists during the whole 

 duration of the parasitic life, and only disappears in the adult when its 

 cuticle is comj^letely chitinized. The fibrous layer in the wall of the 

 intestine is not muscular, but elastic in nature, and its development is 

 more marked as the tube diminishes ; in fact, it is these fibres which cause 

 the contraction of the intestine. 



There is really but one pair of ovaries, but each divides into two 

 tubular branches, while the dorsal canal of Vejdovsky is a fifth impaired 

 and rudimentary branch ; the receptaculum seminis is homologous with the 

 ovaries ; various points in which Vejdovsky appears to be in error with 

 regard to the genital organs and the parenchyma are indicated. 



The Gordiidse are essentially characterized by their embryonic rostrum 

 and the structure of their genital organs, as well as by the relative superiority 

 of their integument, parenchyma, muscular and nervous system, and they 

 should be distinguished from the Nematodes. 



Development and Determination of free Gordii.* — M. A. Villot urges 

 again attention to certain points in the life-history of Gordiufi, which appear 

 to be still insufficiently recognized. They are : (1) these parasitic worms 

 may leave their hosts at very different stages in development ; (2) the 

 chitinization of the cuticle causes, in adult individuals — whether free or 

 parasitic — changes in coloration, form, and structure ; (3) individuals of 

 the same species may, even when completely developed, present very con- 

 siderable difierences in size. Having given evidence in support of these 

 statements, the author proceeds to point out the importance of their bear- 

 ing on the specific distinctions of various Gordii. We must be careful 

 only to compare individuals of the same sex and age- — in other words, forms 

 of the same degree of chitinization, and we must be careful about the diifer- 

 ent phases of the chitinization of the cuticle in individuals of the same 

 species. The forms lately described by Camerano — G. Perronciti, G. Rosse, 

 and G. Piottii, are all examples of the polymorphous G. oquaticus (or 

 G. suhspiralis). To be quite certain about the characters of a species of 

 Gordius a large series of specimens must be compared. 



Brown Cysts of Anguillula of the Beetroot. f — M. J. Chatin finds that 

 under certain circumstances, and especially on the approach of winter, the 

 females of Heterodera Schachtii undergo peculiar changes. The delicate 

 integument gradually thickens, its glands furnishing an abundant secretion, 

 which agglutinates organic and mineral substances, and so forms a sort of 

 adventitious test around the female; this carapace closes up the buccal, 

 anal, and vulvar orifices, and all connection between the worm and nourish- 

 ing plant is broken. We have now a cyst filled with eggs, and comparable 

 to an ootheca. It is easy to see how such a cyst can withstand the in- 

 fluences of bad weather. Later on, under more favourable conditions, the 



* Zool. Anzeig., x. (1887) pp. 505-9. t Comptes Kendus, cv. (1887) pp. 130-2. 



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