268 80 



the colonies have an almost incredibly chaotic appearance, but commonly the tran- 

 sitional periods are brief. Unfavourable conditions prolong these periods. Powers 

 could further show that exhaustive nutriment, for instance copious feeding with Moina, 

 not only gave rise to the campanulate form, but also the humped forms, deriving 

 from it, which possessed very long, highly developed humps that may be so long 

 that they exceed the animal's length. It is supposed that each of the minor fluc- 

 tuations which the three forms of the species undergo, will almost certainly resolve 

 themselves into factors of nutrition. 



Powers has pointed out the very essential fact that the above-named three 

 forms are all able to produce males, and that these males all have the same appear- 

 ance; they are produced copiouslj' by the humped and campanulate types, rarely 

 and only in distinct periods by the saccate type; the size of the males varies greatly, 

 from 300 to 1500 /(. Also the resting eggs are produced by all three forms, rarely 

 by the saccate; in the humped three to six, rarely nine, are seen; in the campanulate 

 also a high number. 



It will be understood that the saccate form in almost all respects is very near 

 to A. Brightivelli. The main difference between A. amphora and A. Brigbtwelli is that 

 the trophi of the lastnamed species invariablj^ lack the large inner tooth, whereas 

 it is always well developed in all three forms of A. amphora. Powers has however 

 found a population of A. Brighlivelli, where the trophi bore a strong inner tooth in 

 the exact position in which this is found in A. amphora. He has further shown, 

 that parallel cultures with identical conditions as to food and temperature, the one with 

 the saccate forms of A. amphora, the other with the tj'pical A. BrighhveUi, invariably 

 gave the same results; the saccate forms gave the humped forms; A. BrighhveUi al- 

 ways A. BrighhveUi; further that cultures of A. BrighhveUi with inner tooth, continued 

 over 6 weeks, invariably only gave the same type. He therefore concludes, that A. 

 amphora and BrighiweUi are really distinct species, and that there may be found 

 special races also in BrighhveUi. 



The colony which I found in August in the above-named little pond contained 

 the species in enormous masses. The main form was the above described humped one, 

 but among them were numerous giants of the campanulate form, often measuring about 

 2000 fi; a very few specimens of the saccate form occurred; only the two first-named 

 forms produced males; these were always humped. As far as I know, this is the first time 

 after Power's investigations that the species with all its three forms was found. The 

 campanulate form fed upon the humped form and upon the young ones of Daphnia. 

 In September resting eggs appeared in the humped and the campanulate form. In the 

 last part of October the males disappeared, the humped ones became rarer and rarer, 

 and in the first days of November only a few very large campanulate forms remained. 

 By 15/XI Asplanchna was found no more. In December we had a short frost period; 

 the pond thawed again and was finally frozen about 6/1 22. The very interesting 

 discovery occurred at a moment when I was verj' much occupied with studies re- 

 lating to other Rotifers, and I was unable to pay as much attention to the colony 



i 



