280 ANNUAL KECORD OF SCIENCE AND INDUSTRY. 



first and most powerful impress." American Journal of 

 tScience and Arts ^ October^ 1876. 



ORIGIN OF THE SEXES IX VEGETABLES AND ANIMALS. 



Some facts tending toward an explanation of this subject 

 have been afforded by Henneguy in his studies on the Yol- 

 vox, a low plant. He finds that during a certain period the 

 Volvox is multiplied by a sexual generation, by fission (scis- 

 siparity) of a vegetative cell, which by successive segmenta- 

 tions produces a colony of individuals similar to the mother- 

 colony to which this cell belonged. But a time comes when 

 the vegetative cell no longer possesses the property of repro- 

 ducing itself thus; it can still, however, divide into seg- 

 ments, and give birth to a colony of little cells which acquire 

 a sexual character ; that is to say, they are incapable of liv- 

 ing separately and of reproducing themselves. This abortive 

 daughter-colony constitutes the male element, endowed with 

 movement, and still enjoying a certain activity. Soon the 

 vegetative cell becomes incapable of segmenting; it can 

 only increase in volume : it is the female element dei^rived 

 of motion, which requires, in order to reproduce itself, to fuse 

 with the male element. Sexuality in Volvox appears then 

 by degrees, the male sex appearing before the female sex as 

 fast as the species exhausts itself by a sexual reproduction. 



We must compare this fact, says Henneguy, with w^hat 

 takes place in the animal kingdom in those animals which 

 are reproduced by parthenogenesis. Professor Balbiani has 

 observed that certain Aphides and the Phylloxercie degenerate 

 when they are reproduced during a certain time by partheno- 

 genesis ; their genital and digestive organs tend to become 

 atrophied. There is a time when the parthenogenetic indi- 

 viduals thus degraded give origin first to male individuals, 

 then to female individuals, which require to be fecundated to 

 reproduce new parthenogenetic individuals. Aim. Mag. of 

 Natural History^ September. 



THE BORDER-LINE BETWEEN PLANTS AND ANIMALS. 



The boundary-line between animals and plants has again 

 been effaced by the studies of Cienkowsky on a monad {Diplo- 

 phrys stercorea). These little bodies, which he observed in 

 moist horse-manure, multiply by division, and form, by the 



