On the Agamic Reproduction of a Species q/" Chironomus. 31 



small shot, the chase was productive of nothing more substan- 

 tial than excitement. From the experience gained from the 

 race, the pace at which the seals go through the water may 

 be considered between six and seven miles an hour. 



Colonial Museum, Wellington. 

 April 3, 1871. 



IV. — On the Agamic Reproduction of a Species of Chiro- 

 • nomus, and its Development from the Unfecundated Egg. 

 By OscAE VON Geimm *. 



[Plate in.] 



Introduction. 



" Nature goes on her ■way, and what seems to us an exception is 

 according to rule." — Goethe. 



Although the parthenogenesis, that is to say the agamic re- 

 production, of many insects (such as the worker bees, humble 

 bees, wasps, ants, Coccidse, &c.) had long been known, 

 people were disinclined to put any faith in the discovery of 

 Prof. N. Wagner, of Kasan, that the larva of a Cecidomyid 

 propagates asexually. For fully two years Wagner's dis- 

 covery had to submit to unmerited mistrust, although it had 

 been crowned with the Demidow prize by the St. Petersburg 

 Academy of Sciences ; and it was only in the year 1863 that 

 it was published in the ' Zeitschrift fur wissenschaftliche Zoo- 

 logie.' But however incredible the fact discovered by Wagner 

 might appear, it had at last to be accepted when it was com- 

 pletely comfirmed by the investigations of Meinert, Pagen- 

 stecher, Leuckart, Ganin, and Metschnikow. Nevertheless 

 this alternation of generations among insects is regarded as 

 an extremely rare case, although, in my opinion, we possess 

 no satisfactory reasons for limiting it to a few insects ; on the 

 contrary, among the Diptera it appears to occur frequently, and 

 although not in the greater number of these insects, still by 

 no means only in a few isolated cases. 



In the spring of last year (1869) I found in my aquarium 

 a great number of ova, which afterwards proved to be those of 

 a species of Chironomus, and which I employed for the inves- 

 tigation of the embryonic development. But when I surprised 

 the egg-laying animal itself engaged in oviposition, I could 

 not but subject it to a close examination, especially as it 

 proved to be an imperfectly developed insect. I had conse- 



* Translated by W. S. Dallas, F.L.S., from the ' Memoires de I'Acad. 

 Imp. des Sciences de St. Petersb.' 7^ ser. tome xv. 



