180 M. E. Claparede on the Formation of the Egg 



through, the contents flow forth in the form of a coherent mass. 

 If we now examine a portion of the tube situated rather lower 

 down, we find larger granules arranged in the axis of the organ. 

 These form the first commencement of the rhachis, which gra- 

 dually becomes broader and darker, whilst the periphery of the 

 contained mass appears mamillated. When the genital tube is 

 torn up with needles, this contained mass is observed to consist 

 of pyramidal eggs, of which the apices adhere to the rhachis, 

 whilst their bases form hemispherical elevations at the peripherj^ . 

 The question now is, whether this rhachis be a true one, or only 

 apparent, as Meissner asserts. The rhachis is a true one ; upon 

 this point there can be no doubt. In Ascaris suilla, in which 

 the rhachis is very thick, it is easy, by means of needles, to strip 

 off most of the eggs from the rhachis, and obtain long pieces of 

 the latter in a free state. We may then convince ourselves that 

 the rhachis really forms a continuous column, and that it does 

 not consist of a series of germinal cells. In Ascaris mystax, in 

 which the rhachis is much thinner, this preparation does not 

 certainly succeed so easily; but here also the conditions are 

 exactly the same. Both in Ascaris mystax and in A. suilla, but 

 especially in the latter, it is easy to obtain the stellate groups of 

 eggs which Meissner has figured and described as germ-cells 

 with eggs adhering to them. These, however, are mere artificial 

 productions, which may be prepared at pleasure by tearing away 

 small pieces of the rhachis. It is very remarkable that Meissner, 

 although he discerned this circumstance very accurately in 

 Strongtjlus armatus, nevertheless still maintains his perfectly 

 false theory. 



Bischoff and Meissner have disputed gallantly as to whether 

 the eggs are or are not furnished with a vitelline membrane 

 within the vitellogeue. In our opinion, however, this is a 

 trifling dispute, which has already cost far too many words, but 

 has thriven to such an extent, that it must cost a few more. It 

 might have been desirable that the combatants, before arming 

 themselves for the battle, had first ascertained clearly what they 

 understood by membrane. This is a notion that forces itself 

 upon us involuntarily when we read Thompson's memoir. This 

 observer denies* the existence of the membrane, because the sm*- 

 face of the eggs appears exactly like that of a Proteus [Amceba). 

 But the difiiculty is by no means got rid of in this way, for 

 there is no question so imsettled at present, as that of the pre- 

 sence or absence of an enveloping membrane in the Amoeba. It 

 is only recently that Auerbachf has brought forward reasons in 



* hoc. cit. p. 435. 



t Ueber die Einzelligkeit der Amccben. Zeitschrift fiir wiss. Zool. 

 Bd. vii. Heft 4. 



