286 PROCEEDINGS OF THE ACADEMY OF [1897. 



exactness. 5 He forces one to realize that it is far more wonderful 

 that nature proceeds with almost absolute regularity in the develop- 

 ment of organs if we take into consideration the minuteness of the 

 vegetative point and the quite incomprehensible precision with 

 which molecules must travel each to its particular place of destina- 

 tion. He adds "a few molecules which stimulate the formation of 

 anthers might be supposed to deviate the toVt part of a millimeter to 

 the right or to the left of their prescribed path, or they might be 

 delayed two or three minutes on their journey " and produce an ab- 

 normal growth. Thus it is that in the crowded condition of the 

 floral organs at the growing point and because of the complex dif- 

 ferentiation which must take place here at a very early period, that 

 monstrosities in flowers are comparatively frequent. 6 Internal 

 hereditary tendencies, no doubt, come to the fore-ground in a greater 

 or less degree ; certainly in the most pronounced manner in such 

 cases e. g., as those cited by Sachs in the Iridacese where the inner 

 circle of stamens reappears at times as an abnormal development, 

 and thus the type of the Liliaceseis repeated. Sachs maintains that 

 we might regard the normal Iris type as a monstrosity. 7 It is quite 

 apparent, however, that such distinctions will depend entirely on the 

 accepted definition of the term monstrosity. It seems reasonable to 

 suppose that the more complex the condition of an undeveloped tis- 

 sue mass the greater the possible amount of displacement from the 

 normal position, and the less marked externally will be the influ- 

 ence of hereditary tendencies. In undeveloped foliage leaves where 

 the young parts are apt to exert less influence, and are in their turn 

 less dependent on the condition of adjacent tissues we might, per- 

 haps, expect at times to find in abnormal growths an innate ten- 

 dency of an entire family. 



I will describe in brief another and very different case of mon- 

 strosity observed at about the same time as the above. The plant 

 was the common garden hydrangea, Hydrangea hortensis L. Near 

 the end of a shoot and opposite a perfectly normal leaf, I noticed one 

 which was composed of two distinct blades. These were united by 

 the midrib from the base upward about half the length of the leaf, 

 and from there on the blades were completely separated. Plate V, 

 fig. 4, is a side view of the double leaf. It was interesting to note 



5 Ibid. p. 236. 



6 Ibid, p. 235. 



7 Ibid. p. 234. 



