346 GRESSWELL SHEAIJKK. 



ampliiasters in the stage now under discussion were ruptured 

 just before the worm containing them was placed in Hermann's 

 fluid. The cytoplasm had flowed or been pressed out of the 

 ovum, carrying with it the amphiaster. In both cases the 

 cytoplasmic network had been completely bent and twisted 

 into a confused snarl. The achromatic rays were somewhat, 

 but not nearly so much distorted, but the centrospheres were 

 almost unchanged. From this I infer that the amphiaster 

 and the rays are, on the whole, much more rigid than the 

 cytoplasmic network or the cytoplasm from which they are 

 formed." Evidently the same thing took place in this 

 instance as I have observed in Histriobdella, where the 

 large size of the spindle and the granular nature of the egg 

 renders the various steps in the process clearly visible under 

 the microscope. 



By pricking the egg-membrane of Allolobophora, Foot 

 and Strobell (9) have been able to get the egg contents on 

 the slide, and there pliotograph it after fixation. " By this 

 method the germinal vesicle, and sometimes even the spindle, 

 flow out of the egg-membrane intact" (p. 201). Some 

 excellent photographs are shown of these in figs. 125-130 

 of this paper. In Allolobophora, as in Histriobdella, 

 the early stages of the first maturation division are gone 

 throuo-h by the egg while it is still within the receptacula 

 ovorum. 



10. Conclusion and Slmmary. 



Harmer (12) was the first to point out that Histriobdella 

 was more closely related to Dinophilns than to any other 

 Archiannelid, although Pierantoni (26), in his recent mono- 

 graph, has placed Histriobdella and Dinophilus as an 

 appendix to the PolygordidtB (including Protodrilus). 

 Schimkewitsch (28) has contended that Dinopliilus is closely 

 related to the Rotifers, and Haswell (13) has put forward a 

 similar claim for Histriobdella. In Histriobdella it is 

 certain that the parasitic mode of life has resulted in a 

 peculiar specialisation, which, combined with its direct mode 



