186 OVARY AND PAROVARIUM, BY W. WALDEYER. 



be distinguished by the eye from the principal yolk mass. I 

 shall return to the objections which may be raised to this view 

 from a consideration of the total cleavage undergone by the 

 Batrachian ova. 



The vitelline lamellw just mentioned, found in the ova of 

 the Chelonia, Batrachia, Cartilaginous Fishes, and of many 

 Osseous Fishes, are doubly refractile crystals (Radlkofer) of an 

 albuminous substance, that Kiihne, in his "Physiological 

 Chemistry," p. 552, has stated to be vitellin. Virchow (119) 

 first established their albuminous nature by their micro- 

 chemical reactions, and showed that they at least do not 

 consist of fat, as had been previously held. The form of the 

 crystal varies in different species, being four-sided plates, 

 frequently with produced angles, in the Frog, whilst in the 

 Perch very various forms occur, that for the most part change 

 into spheres in the mature ovum. (See Radlkofer, 113). 



I will add to these remarks on the ova of Vertebrata a few 

 words on the ovaries and ova of the Invertebrata. The obser- 

 vations of Lieberkuhn (69) on the Porifera, those of Balbiani 

 (8) and Stein (110) on the Infusoria, and those of Greeff (48) 

 and Stre thill Wright (112, 113) upon the Rhizopods, have 

 furnished us with some information on the uniform and 

 remarkable relations occurring amongst the PROTOZA, though 

 our knowledge in regard to them is still extremely imperfect. 



The ova of the Porifera are not developed in special organs, 

 but the several epithelial cells (?) of the walls of the system of 

 canals traversing the sponge mass are capable of developing 

 into ova. 



In the Infusoria, according to Balbiani, a female organ first 

 occurs as a special structure in the form of the so-called nucleus. 

 This varies much in shape, being round, oval, or even band- 

 like ; its granular contents, which resemble protoplasm, in the 

 act of conjugation of two infusory animalcules which precedes 

 fertilization, divides into several portions by a kind of cleavage, 

 and it is still questionable whether we must regard the nucleus 

 as a single ovum, or these products of cleavage as ova, and the 

 nucleus consequently as an ovarium, which must then consist 

 simply of germinal matter without any tissue-forming inter- 

 mediate substance. 



