Chap. XXIII. CONDITIONS OF LIFE. 279 



half or one-quarter a nectarine, and the other half or three- 

 quarters a peach. Again, seven or eight varieties of the 

 peach have yielded by hud- variation nectarines : the nectarines 

 thus produced, no doubt, differ a little from one another ; 

 but still they are nectarines. Of course there must be 

 some cause, internal or external, to excite the peach-bud to 

 mange its nature; but I cannot imagine a class of facts 

 better adapted to force on our minds the conviction that 

 what we call the external conditions of life are in man}' cases 

 quite insignificant in relation to any particular variation, in 

 comparison with the organisation or constitution of the being 

 which varies. 



It is known from the labours of Geoffroy Saint-Hilaire, and 

 recently from those of Dareste and others, that eggs of the 

 fowl, if shaken, placed upright, perforated, covered in part 

 with varnish, &c, produce monstrous chickens. I\ow these 

 monstrosities may be said to be directly caused by such 

 unnatural conditions, but the modifications thus induced are 

 not of a definite nature. An excellent observer, M. Camille 

 Dareste, 59 remarks " that the various species of monstrosities 

 "are not determined by specific causes; the external agencies 

 " which modify the development of the embryo act solely in 

 " causing a perturbation — a perversion in the normal course of 

 " development." He compares the result to what we see in 

 illness : a sudden chill, for instance, affects one individual 

 alone out of many, causing either a cold, or sore-throat, rheu- 

 matism, or inflammation of the lungs or pleura. Contagious 

 matter acts in an analogous manner. 60 We may take a still 

 more specific instance : seven pigeons were struck by rattle- 

 snakes : 61 some suffered from convulsions ; some had their 

 blood coagulated, in others it was perfectly fluid ; some 

 showed ecchymosed spots on the heart, others on the intestines, 

 &c. ; others again showed no visible lesion in any organ. It 

 is well known that excess in drinking causes different diseases 



5Q ' Memoire sur la Production his ' Vie, Travaux,' &c, 1847, p. 290. 

 Artificielle des Monstruosites,' 1862, 60 Paget, ' Lectures on Surgical 



pp. 8-12; ' Recherches sur les Condi- Pathology,' 18.j'3, vol. i. p. 483. 

 tions, &c, chez les Monstres,' 1863, 61 ' Researches upon the Venom of 



p. 'i. An abstract is given of the Rattle-snake,' Jan. 1861, by Dr. 



Geoffroy's Experiments by his son, in Mitchell, p. 67 



>i . 



