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 bud-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 

 change 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 many 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. Now 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, 

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

 is well known that excess in drinking causes different diseases 



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



Artificielle des Monstruosites,' 18^2, 60 Paget, ' Lectures on Surgical 



pp. 8-12 ; ' Recherches sur les Conai- Pathology,' 1853, vol. i. p. 483. 



t : ons, &c, chez les Monstres,' 1863, 61 ' Researches upon the Venom of 



p. 6. An abstract is given of the Rattle-snake,' JaD. 1861, by Dr. 



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



