102 PROCEEDINGS OF THE ACADEMY OF [1899. 



With these facts in mind the occasional facing of each other in 

 leaves of Lactuca Scariola and other plants becomes explainable 

 under the varying degree of energy expended in the uncoihngs of 

 the spiral at different times and localities in the growth of the 

 parts. 



An interesting fact in connection with inheritance presented itself 

 in this investigation. As already noted, the plants from the 

 sohtar}' individual varied in numberless ways. The second year's 

 crop had in the main the characters of the parent ; but there were 

 groups here and there which, while varying among themselves, 

 would have the general characteristics of the first variation. For 

 instance, there would be a group of pinnatifid -leaved plants, though 

 with variations in breadth and length, in the divisions of the lobes, 

 and in other respects differing among themselves ; while in other 

 spots would be groups with leaves wholly entire, and other groups 

 with serratures. The seeds from some single plant, reaching the 

 ground together in one place, probably accounted for this. It is at 

 any rate a good illustration of inheritance going along in parallel 

 lines with variation. 



IX. The stigma of Asclepias. 

 While preparing the chapter on Asclepias tuberosa for my illus- 

 trations of the Flowers and Ferns of the United States, continued 

 as Meehans' Monthly, I noted glandular callosities, not hitherto 

 recorded as being observed, indicating abortive floral organs. It 

 led me to a review of our former beliefs in regard to the structure 

 of these cui'ious flowers. The first morphological difficulty was the 

 supposed five-lobed stigma. With our modern knowledge of 

 morphology it seemed incredible that a flower formed on a quinary 

 plan, losing finally by abortion three or four of its carpels when 

 forming the fruit, should yet have a five-lobed stigma at the apex 

 of its ovarium. A careful examination satisfies me that the 

 accepted view is wrong. The mass forming the supposed stigma is 

 wholly independent of the carpellary system. Indeed, there is no 

 departure from the morphological laws prevaihng in flowers gen- 

 erally. Keeping in mind the power of union and segregation, 

 and of arrest and retardation in the development of floral organs, 

 the structure of the flower in Asclepias will be found exceedingly 

 simple. There is no occasion for the mystery brought in generally 



