ZOOLOGY: a H. PARKER 
437 
Finally, and this applies to all the regions involved, there is to be taken 
into account the many species, weeds and cultivated plants, which have 
been introduced through the agency of man. A study of these immi- 
grants — the origin of most of which can be fairly well ascertained, espe- 
cially when they have been long established in their new habitat — 
ought to be one of the best means of determining the effects, if any, of 
a changed environment. The vexed question of the inheritance of such 
acquired changes can thus be studied on a large scale and under normal 
conditions. It is surprising that so little attention has been paid to this 
great field by the many students of mutation and genetics who set the 
fashions in biology just now. 
These are but a few of the many problems which might be undertaken 
by the botanist in this vast region which it is proposed to explore. It is 
perhaps presumptuous for one whose work has been mainly in other 
directions, to suggest what are the most important lines of work in 
fields in which he is very much of an amateur. 
NERVOUS TRANSMISSION IN SEA-ANEMONES 
By G. H Parker 
ZOOLOGICAL LABORATORY OF THE MUSEUM OF COMPARATIVE ZOOLOGY AT 
HARVARD COLLEGE 
Received by the Academy, June I, 1916 
The retraction of a sea-anemone Hke Metridium can be accomplished 
by stimulating mechanically almost any point on its exterior. Hence 
there must be nervous connections between all points on the surface 
open to stimulation and the longitudinal muscles of the mesenteries 
by which retraction is brought about. To ascertain how extensive 
these connections are, the following experiments were tried. The 
column wall of a Metridium was completely girdled by a cut deep 
enough to penetrate the wall but not sever the mesenteries. Stimu- 
lation of either the oral or pedal portion of the partly divided animal 
resulted in general retraction. Complete removal of the oral half left 
the pedal half capable of retraction. Tongues of column wall cut in 
any direction and as long as five centimeters transmit when stimulated 
at their free ends to the longitudinal muscles thus causing retraction. 
If a Metridium is cut through vertically except for the pedal disc or a 
piece of the column or the oral disc, the stimulation of one piece will 
cause the whole animal to retract. If an oblong outline is cut on the 
column Vv^all so that the encircled area remains attached to the rest of 
the animal only by the mesenteries, stimulation of this area is followed 
