72 



places of growth, 1 was never able to find either larvæ, eggs 

 or spermatozoa. This is in all essentials in accordance with the 

 results arrived at by Kraepelin with respect to North Ger- 

 many (see W.-L. 1897 p. 344 — 349) and further corresponds 

 with Zschokkes reports on his researches respecting Bryozoa 

 in high Alpine lakes. Zschokke states, that he has never seen 

 any sexual elements in the Plumatella colonies of lakes in- 

 vestigated by him, and that these Alpine Bryozoa possibly — 

 he does not wish to express himself positively — may prove 

 to form an interesting parallel to the colonies of the northern 

 regions (1900 p. 119). Thanks to Kraepelins investigations 

 we now know that in North Germany Paludicella produces eggs 

 as well as spermatozoa, a feature which will probably also hold 

 good with us. The larves have only once been found in the 

 vicinity of Breslau (Bräem 1896 p. 54). Since then I have 

 continually been in search of them in and on the large Palu- 

 dicella colonies in Fure- and Lyngby-Sø but as yet without 

 success. Whilst neither Kraepelin nor 1 have ever seen the 

 Fredericella larva, Chirica (1904 p. 2) reports, that in the 

 Rumanian lakes the Fredericella throw off their larves in the 

 latter end of July; these larva haves further been observed by 

 Bräem as far as I know near Breslau (1896 p. 503). 



In our latitudes the production of eggs and sperms along 

 with a copious produce of larvae can only be regarded as a 

 common feature in Plumatella repens^ fungosa and in Crista- 

 tella. Further researches must now decide, whether not only 

 the forms, that already with us seem to have abandoned more 

 or less the sexual mode of reproduction {Fredericella, Pluma- 

 tella fruticosa and possibly also Paludicella Ehrenbergii) but 

 likewise all the rest of the Plumatella species as well as Cri- 

 statella, both of which will in time presumably be found in the 

 arctic region, and which in our latitudes all produce larvae 

 abundantly, only propagate asexually in the far north. This 

 would seem the more probable, as the arctic conditions un- 



