The life histoiy of Diplodiscns teniporatus Stafford. 621 



comparison with the development of the eggs in the hermaphro- 

 ditic sexual generation will be of interest. 



Schubmann (1905) in his study on the oogenesis of Fasciola 

 Jiepatica finds that the oocytes become separated from the walls of 

 the ovarium over a greater part of their surface, but that they 

 remain for along time connected with the wall through a narrow 

 strand of cytoplasm. His figg. 2, 3. 4, and 12, tab. 34, represent a 

 conditions such as is commonly found in the ovary of the sporocysts 

 of DiplocUscus : as is shown in Fig. 13. Concerning the function of 

 this cytoplasmic connection he says: "Ähnlich wie bei Ascaris 

 megalocephaJa, glaube ich, daß auch bei Bistomimi hepaticum der Ei- 

 stiel die Hauptaufgabe hat, dem wachsenden Ei Nahrung zuzuführen. 

 Diese Vermutung glaube ich stützen zu können durch die Tatsache, 

 daß ich im Eistiel stets dunkle, körnige, unregelmäßige Partikel sah, 

 die sich dort, wo der Stiel in die Oocyte übergeht, besonders zahl- 

 reich finden. Die Partikel sind der Eizelle durch den Stiel zu- 

 geführte Nahrungsmassen. In den figg. 2, 3, 4 sieht man deutlich, 

 wie diese dunkler gefärbten Körperchen in die Zelle hineinrücken, 

 um von dieser als Nahrung aufgebraucht zu werden." 



Kerbeet (1881) describes the same appearence of the oocytes 

 in Distomum wesfermarmi, but gave to it a very difi'erent inter- 

 pretation. He considered the pedicle to be a long thin amoeboid 

 process of the egg cell. He makes no mention of any special func- 

 tion for this part of the cell and apparently considered its relation 

 to the wall of the ovarium to be simply contact instead of cyto- 

 plasmic continuity. 



The Maturation of the Parthenogenetic Eggs. 



Grobben (1882), Leuckart (1882) and Schwarze (1886) held 

 that the germ cells within the nurse generations of the Malaco- 

 cotylea were true parthenogenetic eggs, and that consequently the 

 life cycle was heterogenesis. 



BiEHRiNGER (1884) Characterized the development as "internal 

 budding". Schauinsland (1883) described the developmental cycle as 

 a true alternation of generations, to which he gave the special name 

 Alloiogenesis. 



Looss (1892) characterized the development as a metamorphosis, 

 he says: "Die Entwicklung aller Formen kann ohne Zwang auf- 

 gefaßt werden als eine Metamorphose, welche auf mehrere Genera- 

 tionen sich verteilt (Sars, Leuckaet). Der Annahme einer Partheno- 



Zool. Jabib. XXVIII. Abt. f. Anat. 41 



