388 T. B. ROSSETER ON HOLOSTOMUM EXCISUM, AND THE DEVELOPMENT 



the oval body, the motile 'and inert stage, and also the inert 

 capsuled stage ; but here the transition ends. 



This important and masterly work of Linstow on Tetracotyla 

 typica seems to me to be a justification of a previous paper by the 

 same author (with which I am unacquainted) and concerning 

 which Dr. G. Brandes, in " Die Familie des Holostomidae," ZooL 

 JahrbilcJter (Jena, 1890), questions the accuracy of Linstow's 

 conclusions as regards the development of the egg into a 

 ciliated embryo and then into an embryonic or larval Tetra- 

 cotyle. Dr. Brandes admits that in Kuchenmeister's diagnosis 

 of the changing embryo there are points which refer to its 

 Tetracotyle development. He is not satisfied, however, with 

 Ercolani's assertion of his having produced a Holostomum by 

 feeding ducks and sparrows on molluscs infested with Tetracotyla 

 typica. Further, he is not in accord with von Linstow's theory 

 of cell development. He had hoped to fill up the gaps left by 

 Linstow, but says his eggs were attacked by a fungoid growth, 

 and destroyed. Nevertheless, he was in a position to state that 

 at the most only a second division of the nucleus takes place ; 

 that rejuvenation occurs (between the yelk cells at the pole of the 

 eggs) ; and that he could substantiate Schauinsland's assertion 

 that the protoplasm participates in the division of the nucleus. 

 Brandes frankly states that in his clay much that had been 

 written on the development of the family Holostomidae was exag- 

 gerated. The knowledge of the circumstances attending the 

 change from the larva to the sexually mature Holostomum was 

 no more advanced than that concerning the embryo ; and apart 

 from Ercolani's single sketch of the largely increased body of the 

 Holostomum (which he questions) he admits that he has nothing 

 new to add. He relates how he had fed an owl (Otis vulgaris) 

 with horseflesh containing six specimens of Tetracotyla taken from 

 the tissue of a ringed snake (Tropidonotus natrix), but unfortu- 

 nately his owl died prematurely, and although in the autopsy 

 he did find a questionable specimen of Holostomum in the 

 intestine, he attached no importance to it, as it did not prove 

 the metamorphosis of the Tetracotyla into a sexually matui*e 

 Holostomum or Diplostomum. In his own mind Brandes is 

 not sure that the owl is the true host for the development 

 of the Tetracotyla, and it certainly requires more than one 

 feeding experiment to demonstrate the different stages of" 



