III. On the course of the fibres of the cingulum and the posterior parts of the corpus callosum and fornix in the marmoset monkey

Abstract

There are various methods which have been adopted to work out the course of the fibres in the brain. The method by dissection of the brain with the scalpel has been much employed, and though it is doubtless of value in tracing out the coarser strands, it is open to the objection that the parts are very much displaced by the operation necessary to follow out the fibres, and also that relations may be artificially produced which do not actually exist. Moreover it is quite impossible to trace the fibres to their ultimate ending, as this can only be accomplished by the use of the microscope. The methods of tracing the fibres by producing degeneration in the different tracts by dividing them during life, and also the method of examining the period in fœtal life at which the fibres acquire their medullated sheath, which has been employed by Flechsig, give most certain results, but they present great difficulties when a large system of fibres like the cingulum, which courses round the whole extent of the brain, has to be minutely examined.