146 BOTANICAL GAZETTE [FEBRUARY 
Norte.—Since submitting the above for publication there has ap- 
peared an extensive study of abortive stamens by CURT SCHWARZE.* 
The author does not discuss the Compositae in this connection at 
all, nor does he refer to any recent work on that group. On the 
whole it presents very interesting corroborative evidence bearing 
on the conclusions reached above, when properly interpreted. 
Dr. ScHWARZE Calls attention to SCHUMANN (1890) as the originator 
of the theory that reduction of stamens comes about through 
mutual external pressure of the organs in the bud. As opposed to 
this, he presents the contentions of FAMILLER (1896), Mutu, and 
others that abortion is due to internal factors, and himself suggests 
that these internal factors are constitutional in the protoplasm. 
This internal causation hypothesis is based on the failure in some 
cases to observe the parts in actual contact during development. 
It is evident that this is a very difficult point to demonstrate, as it 
necessarily involves disturbing the organs, which may itself sepa- 
rate surfaces loosely in contact. Moreover, recent investigations 
have served to greatly emphasize the delicacy of the sensitivity of 
plants to contact stimuli. But even granted that contact does 
not occur during the ontogeny of certain forms, there is still no 
‘reason that SCHUMANN and FAMILLER may not both have a correct 
interpretation. If we presume that the contact and mutual pres- 
sure did occur during the ontogeny of the ancestors of the living 
forms, such as is at present so striking in the Ambrosiaceae dis- 
cussed above, it may be properly concluded with ScHuMANN that 
the pressure did cause an abortion. Such a reduction in size 
and arrest of development at an immature stage would necessarily 
involve a reduced vascular supply. Such a condition would 
doubtless result in diverted nutrition and water supply, which 
after many generations might make development of the stamens to 
maturity impossible even in the absence of mutual pressure. Thus 
by the reduced vascular supply becoming hereditarily fixed, there 
would be an internal cause for the abortion of the stamens, traceable 
to an original external condition. That the vascular supply is thus 
* ScHWARZE, Curt, Vergleichende Entwicklungsgeschichtliche und histologische 
Untersuchungen reduzierter Staublatter. Jahrb. Wiss. Bot. 54:183-243- 1914- 
