OF ARTS AND SCIENCES. 59 



the other hand, the whole suit, from the first to the last, constitute 

 but a single true generation. I would insist upon this point as illustra- 

 tive of the distinction to be drawn between sexual and gemmiparous 

 reproduction. Morphologically, these two forms of reproduction have, 

 it is true, many points of close resemblance, but there is a grand 

 physiological difference, the perception of which is deeply connected 

 with our highest appreciation of individual animal life. 



" A true generation must be regarded as resulting only from the 

 conjugation of two opposite sexes, — from a sexual process in which 

 the potential representatives (spermatic particle and ovum) of two op- 

 posite sexes are united for the elimination of one germ. The germ 

 power thus formed may be extended by gemmation or fission ; but it 

 can be formed only by the act of generation, and its play of extension 

 by budding or by division must always be within a certain cycle, 

 which cycle is recommenced by the new act of the conjugation again 

 of the two sexes. In this way the dignity of the ovum as the pri- 

 mordium of all true individuality is maintained. 



" In the memoir from which this is an extract, I have entered into a 

 full discussion of those many points suggested by these studies. One 

 of these is the relation of this subject to some of the various doctrines 

 of development, which have been advanced in late years, such as that 

 of Alternation of Generation by Steenstrup, and that of Partheno- 

 genesis by Owen. I have there attempted to show that the phenomena 

 of these doctrines, as advanced by their respective advocates, all be- 

 long to those of gemmiparity, and that therefore Alternation of Gen- 

 eration and Parthenogenesis, in their implied sense, are misnomers in 

 physiology. Another point there treated in extenso is the identity of 

 this mode of reproduction we have just described in the Aphididse with 

 that observed in the so-called hibernating eggs of the Entomostraca, 

 and the like phenomena observed in nearly every class of the Inver- 

 tebrata. They are all referable, in my opinion, to the conditions of 

 gemmation, modified in each particular case, perhaps by the economi- 

 cal relations of the animal." 



Dr. Samuel Parkman and Dr. Benjamin E. Getting were 

 elected Fellows of the Academy in the Section of Medicine 

 and Surgery. 



