12 Colouration in Animals and Plants. 



repair of waste and injury, heredity and kindred matters, advanced 

 what he wisely called a provisional hypothesis pangenesis. 



" I have been led," he remarks, " or, rather, forced, to form a view 

 which to a certain extent, connects these facts by a tangible method. 

 Everyone would wish to explain to himself even in an imperfect 

 manner, how it is possible for a character possessed by some 

 remote ancestor suddenly to reappear in the offspring ; how the 

 effects of increased or decreased use of a limb can be transmitted 

 to the child ; how the male sexual element can act, not solely on 

 the ovules, but occasionally on the mother form ; how a hybrid can 

 be produced by the union of the cellular tissue of two plants 

 independently of the organs of generation ; how a limb can be 

 reproduced on the exact line of amputation, with neither too much 

 nor too little added ; how the same organism may be produced by 

 such widely different processes as budding and true seminal gene- 

 ration ; and, lastly, how of two allied forms, one passes in the 

 course of its development through the most complex metamorphoses, 

 and the other does not do so, though when mature both are alike 

 in every detail of structure. I am aware that my view is merely 

 a provisional hypothesis or speculation ; but until a better one be 

 advanced, it will serve to bring together a multitude of facts which 

 are at present left disconnected by any efficient cause.* 



After showing in detail that the body is made up of an infinite 

 number of units, each of which is a centre of more or less indepen- 

 dent action, he proceeds as follows : 



" It is universally admitted that the cells or units of the body 

 increase by self-division or proliferation, retaining the same nature, 

 and that they ultimately become converted into the various tissues 

 of the substances of the body. But besides this means of increase 

 I assume that the units throw off minute granules, which are 

 dispersed throughout the whole system ; that these, when supplied 

 with proper nutriment, multiply by self-division, and are ultimately 

 developed into units like those from which they were originally 

 derived. These granules may be called gemmules. They are 

 collected from all parts of the system to constitute the sexual 

 elements, and their development in the next generations forms a 

 new being; but they are likewise capable of transmission in a 

 dormant state to future generations, and may then be developed. 

 Their development depends on their union with other partially 

 Animals and Plants under Domestication, vol. ii., p. 350. 



