RELATIONS OF OVA AND GEMMAE. 203 



In the Batrachian ovum, on the other hand, Mr. New- 

 port's researches led him to conclude that segmentation 

 never takes place without impregnation, but only certain 

 preliminary changes of a less obvious kind. Even in im- 

 pregnated ova, when, from the excessive dilution or the 

 momentary contact of the spermatic fluid, this process is 

 inefficiently performed, the segmentation stops at its in- 

 cipient stages.* But this result is only what we should 

 anticipate in the ovum of the Vertebrata, in accordance 

 with the general abeyance of gemmation in that division of 

 the Animal Kingdom. 



These facts seem to indicate rather an evanescence, or a 

 feebleness of vitality, than an absolute want of develop- 

 mental nisus in the unimpregnated ovum, as the cause of 

 its general abortion. 



But that the spermatic element is something more than 

 a mere stimulus is shown conclusively by the phenomena of 

 hybridization, and the general fact of the transmission of 

 the paternal peculiarities to the offspring. There are not 

 wanting indications also of a certain intrinsic capacity of 

 development in the spermatic element, at least in plants. 

 Setting aside the power of germination, asserted by some 

 for the spermatia of Fungi, -f- and antheridia of Mosses,j 

 the continued growth of the extremity of the pollen-tube in 

 impregnation, even after the decay of the granule itself, and, 

 according to Schacht, its occasional branching, are well 

 attested facts which look in this direction. It will probably 

 be found also, as observations are multiplied, that the 

 zoospores or motile gemmae of Algss merge by as gradual a 



* Phil. Transact. (1851), p. 169. 



f Berkeley's Introduction to Cryptogamic Botany, 247, 259, note. 



J Lindley's Natural System of Botany, p. 407. 



Schacht on the Microscope (Currey), p. 144. Eeissek maintains the 

 occasional development of pollen grains into fungoid vegetations. Quoted 

 by Sanderson in Cyclopsed. Anat. and Physiol. "Vegetable Ovum," p. 255, 

 note. 



