Videnskabelige meddelelser

Videnskabelige meddelelser


\alue; every real observation is wanting and with good reason

Piersig (1895, p. 301) reproaches him that he has „das unsichere

Gebiet der Spekulation betreten". When, as support for his opinion,

Koenike maintains that Linné has observed the egglaying on

Xepa, this is incorrect. The words of Linné: „Oua nibra in \epis

ponens'' can only be understood so that he has regarded the larvæ

as eggs; they can undobtedly never be understood so, that he has

seen a Hydrachna lay its eggs upon Xepa.

Piersig (1900, p. 459) has probably seen how the eggs are

laid. He says that Duges reports that the female lays the eggs

singly in the twigs. This is a misapprehension of Duges (vide 1834,

p. 165). Besides he has no statement relating to the eggs which

can not be found in Duges. With regard to the larvæ he has

seen that they swim with the capitulum bent in under the body.

Scattered in the litterature we find many observations relating to

the development but most of them are only repetitions and some

of them are undoubtedly wrong.

Krendowsky (1878) reports that he has hatched H. globosa

from Nepa and Ranatra and that he has found the larvæ of Hy-

drachna upon Hydrophilus piceus. Bold (1866, p. 213) has ob-

served that Corixa has a slight orifice in the wings when parasites

are attached to the abdomen under the wings. I have never found

this confirmed and none of the numerous specimens in my coUection

show anything of that. In full accordance with my own observations

Soar (1901, p. 65) maintains that it is impossible to hatch the

nymphs from the waterbugs in September; that a hibernation on

the bugs is necessary for the parasites and that the hatching of

the nymphs goes on in spring. He gives (1906, p. 359) beautiful

illustrations of Dytiscidæ and waterbugs with parasites and indi-

cates that the parasites are fastened very strongly; he has also

seen that the same host has parasites of very different size (p. 364).

He has also hatched H. globosa from Ranatra. Mac Gillary

(1913, p. LIX) indicates that Cybister tripunctatus, India, carries

the larvæ of Hydrachna. Musselius (1914, p. 61) maintains,

that Hydrachna Schneideri lays its abt. 30 eggs in cases of

jelly not pierced into the twigs of water piants. To this statement

a confirmation is necessary. Barrois (1889) supposes that the

Hydrachnidæ in the parasitic stage upon water bugs can be carried

over great distances f. inst. from the Continent to the Agores.

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