42 



clearer and more philosophic view of the subject" (p. 193). 

 This view may be briefly stated to be based upon the belief 

 that ( gemmiparity ' or the process of gemmation is e alto- 

 gether distinct ' from oviparity or the process of develop- 

 ment in and from an ovum ; viviparity being rightly shown 

 by the reviewer to be a mere modification of the process of 

 development from an ovum (pp. 193 and 194). 



Oviparity " is effected by the concurrent agency of two 

 sets of sexual organs, situated on the same individual or 

 appertaining to two different beings ;" and " where there is 

 no evidence of such concurrence, the presumption is" held 

 to be " strong that the reproduction is really carried on 

 upon the gemmiparous plan/' which is defined as " a mul- 

 tiplication of cells by a process of continuous growth" 

 (p. 193.) 



Before entering into the inquiry how far what is known 

 of the process of gemmation is rightly defined as one of 

 ' continuous growth/ as contra-distinguished from the 

 growth of the germ-mass and embryo in an ovum, I feel 

 desirous to offer a few remarks in mitigation of the censure 

 which Dr. Carpenter has passed on the ingenious Essay 

 on the Alternation of Generations. 



When Prof. Steenstrup, for example, in reference to the 

 classes of Invertebrate animals whose generation he has 

 described from his own or others' observations, says that 

 the offspring never resembles its immediate parent, and that 

 the parent " does not meet with its resemblance in its own 

 brood, but in its descendants of the second, third, or fourth 

 degree/' he simply enunciates a matter of fact, and sets forth 

 no hypothesis plausible or otherwise. Unless it can be shown 

 that the ovum of a Medusa does not produce a Hydra Tuba, 

 and this a Strobila from which the Medusa ultimately comes; 

 and unless the cercariform individual which intervenes be- 

 tween the gregariniform one and the Distoma, developing 

 the ova of the Entozoa of the freshwater Snail, have no exist- 

 ence in nature, the language of the ' alternate-generation ' 



