GROWTH AND SEXUAL GENESIS. 457 



sis, visible in these general contrasts, may also be traced in the 

 history of each plant and animal. So familiar is the fact 

 that sexual genesis does not occur early in life, and in all 

 organisms which expend much begins only when the limit of 

 size is nearly reached, that we do not sufficiently note its 

 significance. It is a general physiological truth, however, 

 that while the building-up of the individual is going on 

 rapidly, the reproductive organs remain imperfectly deve- 

 loped and inactive; and that the commencement of repro- 

 duction at once indicates a declining rate of growth, and 

 becomes a cause of arresting growth. As was shown in 78, 

 the exceptions to this rule are found where the limit of 

 growth is indefinite; either because the organism expends 

 little or nothing in action, or expends in action so moderate 

 an amount that the supply of nutriment is never equilibrated 

 by its expenditure. 



We will pass over the inferior plants and, limiting 

 ourselves to Phgenogams, will not dwell on the less con- 

 spicuous evidence with the smaller types present. A few 

 cases such as gardens supply will serve. All know that 

 a Pear-tree increases in size for years before it begins to 

 bear; and that, producing but few pears at first, it is long 

 before it fruits abundantly. A young Mulberry-tree, branch- 

 ing out luxuriantly season after season, but covered with 

 nothing but leaves, at length blossoms sparingly and sets 

 some small and imperfect berries, which it drops while they 

 are green; and it makes these futile attempts time after 



verification. Dr. Dionys Hellin in an essay on the origin of Multiparity 

 and Twin-births, refers to the thesis above set forth, and says that " the 

 fact that it is generally women of small growth who bear twins is in com- 

 plete agreement with it." He adds that " Puech is right in his opinion that 

 twin pregnancies are a direct result of relatively large ovaries (i.e., in com- 

 parison with the whole body). He has observed that for the same size of 

 body the ovarium of a pluriparous animal is always of greater volume than 

 that of a uniparous animal .... a sow has ovaries as large as a cow's ; 

 bnt while the latter bears only one calf [at a timel, the sow brings forth 

 6 15 at each litter. Even in animals of the same species but belonging to 

 different races these relations may be verified," e.g., Barbary sheep and ordi- 

 nary sheep. 



