46 



The metamorphosis was thus not quite completed at Ærø in the middle 

 of June. There were still some pelagic plaice young in the intermediate layers 

 over deep water. 



From our investigations of the plaice eggs and young in 1904 it appears, 

 that the development in the ivestern Baltic is a month hehind that in the northern 

 Danish waters. 



It must be clear to those who have followed our investigations at Ærø, 

 that \ve took no assymmetrical young there in the intermediate Layers over deep 

 water, though \ve fouud the metaraorphosed young ut the coast. If we put all 

 the plaice young taken in the western Baltic in a row, arranged according to their 

 stage of development, we find there is a gap in the row. The young taken iu 

 deep water are all symmetricai, whilst those found at the coast are (juite or almost 

 quite metamor] »hosed. The transition stages are wauting. If we now form another 

 row of the plaice young taken in the northern Kattegat and Skager Rak duriug 

 1904, we find all the transition stages represented there. Considering the whole 

 record, we see that a part of the row comes from Aalbæk Bay, 2 — 4 fm., at the 

 bottom. From this locality we have an unbroken series of developmental stages 

 from the beginning of asymmetry to complete metamorphosis. 



In thus appears, that the plaice yomu/ can pass through all the transition 

 stages from the earliest astimmetry to the completely metamorphosed stage, in the 

 neighbourhood of the coast on or near the bottom. 



This result is confirmed by our investigations at Kerteminde on May 19th. 

 Coneerning these I find the following notes in the journal: 



D. 19 — 5 — 04. We found to-day at Kerteminde a few plaice young on the coast in ca. 

 1 foot of water. We used the "bobinet" and 'halfmoon'' nets and searched for ca. 1 hour. In 

 the latter net we caught 2 plaice of the O group, the smallest 13 mm.; in lioth the wandering 

 of the eye was completed. 



In the "half-moon" net towed after the beat in "„ — 2 fms. we got no plaice young: liut 

 the spread of this net is not very wide (ca. 1 meler), and we cannot expect to find the plaice 

 young so densely distributed in deeper water as near the shore, where tliey crowd together 

 gradually on wandering in. The young-fish trawl was therefore used from the »Sallingsund« in 

 as shallow water as the steamer could conie in to. We made 9 hauls altogetlier each of 7 — 8 

 minutes. The hauls began in 7 — 8 feet of water and were carried out to ca. 2 fm. We succeeded 

 in taking some of the few plaice yomif/ to be found at this depth — in all 7. Of these 2 were 

 almost metamorphosed; the right side of the body was strongly pigmented and the crossing over 

 of the eye was almcst complete. In 4 the left eye was on the ridge. 1 was stiU symmetricai. 



At Kerteminde (Great Belt) we thus found the transition stages at the 

 bottom at a short distance from the shore, as in Aalbæk Bay. 



In the Great Belt the developmental stage on the 19th of May was almost 

 the same as on the 29th of April iu the northern Kattegat and on the 30th of 

 May iu the western Baltic. 



Investigations in earlier years. 



In order to obtain a more complete picture of the occurrence of the plaice 

 eggs and young than the investigations of 1904 can give, we may consider the 

 results of the investigations of earlier years. 



In 1892 the Director found plaice eggs in January — April in Fæuø Sound 

 iu the Little Belt. 



