Page:Proceedings of the Royal Society of London Vol 60.djvu/449

Rh ner as difficult as in the presence of exclusively spinal mechanisms. The reflex inhibitions the subject of this Note show, however, th a t the accessibility is not really greatly or even at all a lte re d ; the nexus is maintained, but the conduction across it is signalised by a different sign, minus instead of plus. The former, to find expression, m ust predicate an already existent quantity of contraction—, to take effect upon. I t seems likely enough th at even w hen th e transection is infrabulbar and m erely spinal mechanisms rem ain in force, the same nexus obtains, but that then that background of tonic contraction is lacking, and that lacking the play of inhibitions remains invisible, never coming within the field of any ordinary m ethod of observation.

Under the conditions adopted in my experim ents, various other reflex actions, that seem probably examples of this same kind of coordination, can be studied, for instance, a sudden depression and curving downward of the stiffly elevated and tonically up-curved tail which can be elicited by a touch upon the perineum. B u t w ith these and also with other details regarding the reflexes at elbow and knee I hope to deal more fully in a paper to which the experim ents recorded here are contributory.

The first indication of the existence of the rem arkable type of fructification about to be described, was afforded by the study of a specimen in the W illiam son collection, from the well-known fossiliferous deposit at Pettycur, near Burntisland, belonging to the Calciferous Sandstone Series at the base of the Carboniferous formation. This specimen is a fragment of stem, of which seven sections are preserved in the collection.* Its discoverer thought it might possibly belong to the Lepidostrobus found in the same bed. “ If so,” he adds, “ it has been part of the axis of a somewhat larger strobilus than those described.” f

A detailed examination of the structure of this specimen convinced me that it is essentially different from any Lepidodendroid axis, and is, certainly, a new type of stem. J

+ Williamson, “ Organisation of the Fossil Plants of the Coal-measures.” Part III. * Phil. Trans./ L872, p. 297. t A short account of this specimen was given by me before the Botanical Section of the British Association at the Liverpool meeting, 1896.
 * The cabinet-numbers are 539—545.