38 M. Oscar von Grimm on the Agamic Reproduction 



accordance with which the embryo is to be built up"*) dividing 

 into two groups (fig. 6), which then pass to the sides of the ovum. 

 We then find that each of tliese groups, consisting of two 

 nuclei, each with a nucleolar corpuscle, is surrounded hj a 

 homogeneous transparent mass, in which a few small hyaline 

 corpuscles are enclosed. This mass has apparently been 

 formed from the embryonal cells and the protoplasm of the 

 polar cells, whilst the large nuclei with their nucleolar corpus- 

 cles, representing the nuclei of the polar cells, originate, as 

 we shall see hereafter, from the germinal vesicles of the ovum 

 or from the nucleus of the ovary of the preceding genera- 

 tion. 



Tlie nuclei of the embryonal ovary (fig. 7) increase by division; 

 and the tertiary nuclei proceeding from them are each sepa- 

 rately sun-ounded by a portion of the common protoplasm 

 with the nucleiform embryonal cells contained in it ; so that 

 we may now regard the whole sti'uctiue as a body which is 

 composed of eight mutually independent cells : the protoplasm 

 of these cells consists partly or, rather, chiefly of nuclei, i. e. 

 embryonal cells. After the lapse of a certain time, when the 

 embryo is already perfectly developed, the ovaries also have 

 become more mature. We now find that the whole ovary has 

 acquired a more elongated form ; and from its superior extre- 

 mity, or that directed towards the head of the embr^^o, there 

 rises a thin filament, and the ovary itself encloses small cor- 

 puscles with a few nuclei, which represent the still imperfectly 

 developed ovarian tubes. 



In these embryonal ovaries, at the first glance, under a low 

 power, we cannot overlook the agreement with those of 

 the Cecidomyid larva as described by Leuckartf, Metsch- 

 nikowj, andGanin§, and even with those of Platt/gaster, 

 according to Ganin !;. But, on a more careful examination of 

 their further development, their diftorence becomes clear : they 

 are in their whole natiire pertectly similar to the ovaries of 

 fully developed insects as described by Clauslj, Leydig**, and 

 others. 



* Weismann, "Die Entwicklun^ der Dipteren im Ei (CTiirouomu^)," 

 Zeit«chr. fiir wiss. Zool. 1868, Rd. xiii. p. 1 15. 



t " IHe iinfreschlechtliche FortpriauzungderCecidomyienlarren,'' Arch, 

 fiir Naturjr. lS(Vi, p. 200. 



X Embr. Studien an Insecten, Taf. 24. fig. 4. 



§ Zapiski Imp. Ak. Pauk. 18Cv5. ^•ii. fig. :\ 



II " Beitruge zur Krkenutniss dor Entwioklungsgesoliicht© bei den In- 

 secten (Plati/f/nsfer)," Zeitschr. fiir wis.-*. Zool. 18t.ii1, Taf. 30. tig. 3. 



% '' Beobachtungen iibor die Bilduiig des Insecteneies," Zeitschr. fiir 

 wiss. Zool. 18(34. 



** Der Eierstock imd die Samentasche der Insecten, 1866. 



